The Trypanosoma cruzi Antigen and Epitope Atlas: antibody specificities in Chagas disease patients across the Americas.

During an infection the immune system produces pathogen-specific antibodies. These antibody repertoires become specific to the history of infections and represent a rich source of diagnostic markers. However, the specificities of these antibodies are mostly unknown. Here, using high-density peptide arrays we examined the human antibody repertoires of Chagas disease patients. Chagas disease is a neglected disease caused by Trypanosoma cruzi, a protozoan parasite that evades immune mediated elimination and mounts long-lasting chronic infections. We describe a proteome-wide search for antigens, characterised their linear epitopes, and show their reactivity on 71 individuals from diverse human populations. Using single-residue mutagenesis we revealed the core functional residues for 232 of these epitopes. Finally, we show the diagnostic performance of identified antigens on challenging samples. These datasets enable the study of the Chagas antibody repertoire at an unprecedented depth and granularity, while also providing a rich source of serological biomarkers.

Tannic Acid, as a Structural Moiety Coupled to a Protein Antigen, Exhibiting a Molecular-structure Adjuvant Activity for Antibody Specificity Enhancement.

BACKGROUND: An antigen is a small foreign substance, such as a microorganism structural protein, that may trigger an immune response once inside the body. Antigens are preferentially used rather than completely attenuated microorganisms to develop safe vaccines. Unfortunately, not all antigens are able to induce an immune response. Thus, new adjuvants to enhance the antigen's ability to stimulate immunity must be developed. OBJECTIVES: Therefore, this work aimed to evaluate the molecular-structure adjuvant activity of tannic acid (TA) coupled to a protein antigen in Balb/c mice. METHODS: Bovine serum albumin (BSA) was used as an antigen. The coupling of BSA and TA was mediated by carbodiimide crosslinking, and verified by SDS-PAGE. Forty-two Balb/c mice were divided into seven groups, including two controls without antigen, an antigen control, an adjuvant control, and two treatment groups. An additional group was used for macrophages isolation. A 30-day scheme was used to immunize the mice. The analysis of humoral immunity included immunoglobulin quantification, isotyping and antigen-antibody precipitation. The analysis of cell-mediated immunity included the quantification of nitric oxide from peritoneal macrophages and splenocytes' proliferation assay after treatment stimulation. RESULTS: No differences were found in the antibodies' concentration or isotypes induced with the conjugate or the pure BSA. However, an immunogenicity improvement (p < 0.05) was observed through the specific anti-BSA antibody titers in mice immunized with the conjugate. Besides, macrophage activation (p < 0.05) was detected when stimulated with the treatments containing TA. CONCLUSION: Tannic acid exhibited macrophages' activation properties. Moreover, when TA was incorporated into the structure of a protein antigen, such as BSA, an antibody specificity enhancement was observed. This was a consequence of antigen processing by activated antigen-presenting cells. These results showed the use of tannic acid as a novel candidate for vaccine molecular-structure adjuvant.

Multiple Tolerization Subtractive Immunization (MTSI) Protocol: Effects on Mice and Monoclonal Antibody Specificity.

Monoclonal antibodies (mAbs) have been a valuable tool to elucidate several biological processes, such as stem cell differentiation and cancer, and contributed to virtually all areas of biomedical sciences. Yet, it remains a challenge to obtain mAbs specific to poorly expressed epitopes, or to epitopes that are actually involved in important biological phenomena, such as cell differentiation and metastasis. Drug-induced subtractive immunization, and recently the multiple tolerization subtractive immunization (MTSI) technique, reported by our group, have the potential to level up the field, as they direct the host´s immune response towards these epitopes. However, due to cyclophosphamide (CY) treatment, high mice mortality can be observed, and only a few data are available on how these techniques affect the immune system of mice. Tolerogen and immunogen cells, RWPE-1 and PC-3 cells, respectively, were individually seeded at 2 × 104 cells/cm2, and then adjusted to 2 × 106 cells per mouse before immunization, which was conducted in a subtractive approach (MTSI) with CY. Immunosuppression of mice was recorded via total white blood counting, as well the reactivity of circulating polyclonal antibodies (pAbs). General parameters, including weight, physical appearance, and behavior on mice subjected to three different concentrations of CY were recorded. mAbs were obtained using classical hybridoma techniques, using the spleen of immunized mice. After purification, antibodies were characterized by Western blotting, and Indirect immunofluorescence. In conclusion, all CY dosage were efficient in creating an immunosuppression state, but only the 100 mg/kg body weight was feasible, as the others resulted in extensive mice mortality. pAbs obtained in the peripheral blood of mice showed more reactivity towards tumor cells. MAbs 2-7A50 and 2-5C11 recognized antigens from tumor cells, but not from their non-tumor counterparts, as shown in western blotting and immunofluorescence assays. MTSI technique was successful in generating mAbs that recognize tumor-specific antigens.

Strong Association of the Myriad Discrete Speckled Nuclear Pattern With Anti-SS-A/Ro60 Antibodies: Consensus Experience of Four International Expert Centers.

Introduction: The morphological patterns in indirect immunofluorescence assay on HEp-2 cells (HEp-2 IFA) reflect the autoantibodies in the sample. The International Consensus on ANA Patterns (ICAP) classifies 30 relevant patterns (AC-0 to AC-29). AC-4 (fine speckled nuclear pattern) is associated to anti-SS-A/Ro, anti-SS-B/La, and several autoantibodies. Anti-SS-A/Ro samples may contain antibodies to Ro60 and Ro52. A variation of AC-4 (herein designated AC-4a), characterized by myriad discrete nuclear speckles, was reported to be associated with anti-SS-A/Ro. The plain fine speckled pattern (herein designated AC-4b) seldom was associated with anti-SS-A/Ro. This study reports the experience of four expert laboratories on AC-4a and AC-4b. Methods: Anti-Ro60 monoclonal antibody A7 was used to investigate the HEp-2 IFA pattern. Records containing concomitant HEp-2 IFA and SS-A/Ro tests from Durand Laboratory, Argentina (n = 383) and Fleury Laboratory, Brazil (n = 144,471) were analyzed for associations between HEp-2 IFA patterns and disease-associated autoantibodies (DAA): double-stranded DNA, Scl-70, nucleosome, SS-B/La, Sm, and U1-RNP. A total of 381 samples from Dresden Technical University (TU-Dresden), Germany, were assayed for HEp-2 IFA and DAA. Results: Monoclonal A7 recognized Ro60 in Western blot and immunoprecipitation, and yielded the AC-4a pattern on HEp-2 IFA. Analyses from Durand Laboratory and Fleury Laboratory yielded compatible results: AC-4a was less frequent (8.9% and 2.7%, respectively) than AC-4b (26.1% and 24.2%) in HEp-2 IFA-positive samples. Reactivity to SS-A/Ro occurred in 67.6% and 96.3% of AC-4a-pattern samples against 23% and 6.8% of AC-4b pattern samples. Reciprocally, AC-4a occurred in 24% and 47.1% of anti-SS-A/Ro-positive samples, and in 3.8% and 0.1% of anti-SS-A/Ro-negative samples. Data from TU-Dresden show that the AC-4a pattern occurred in 69% of 169 anti-SS-A/Ro-monospecific samples (62% of all anti-SS-A/Ro-positive samples) and in 4% of anti-SS-A/Ro-negative samples, whereas anti-SS-A/Ro occurred in 98.3% of AC-4a samples and in 47.9% of AC-4b samples. In all laboratories, coexistence of anti-SS-B/La, but not other DAA, in anti-SS-A/Ro-positive samples did not disturb the AC-4a pattern. AC-4a was predominantly associated with anti-Ro60 antibodies. Conclusions: This study confirms the association of AC-4a pattern and anti-SS-A/Ro in opposition to the AC-4b pattern. The results of four international expert laboratories support the worldwide applicability of these AC-4 pattern variants and their incorporation into ICAP classification under codes AC-4a and AC-4b, respectively. The AC-4 pattern should be maintained as an umbrella pattern for cases in which one cannot discriminate AC-4a and AC-4b patterns. The acknowledgment of the AC-4a pattern should add value to HEp-2 IFA interpretation.

Clinical and Epidemiological Features of Acute Zika Virus Infections in León, Nicaragua.

The American Zika virus (ZIKV) epidemic has highlighted the need to gain a better understanding of this emerging virus. The goal of this study was to describe the clinical symptoms, laboratory findings, and risk factors for symptomatic ZIKV infection in an area with ongoing transmission of other arboviral infections. We recruited patients at least 2 years of age seeking care at public health centers in León, Nicaragua, between January 2016 and August 2017, for fever, maculopapular rash, and/or nonsuppurative conjunctivitis with a duration of less than 1 week. A laboratory diagnosis of ZIKV was established using a combination of molecular and serological tests. Clinical and laboratory findings and potential risk factors were compared between participants with and without acute ZIKV infection. Fifty-eight (26%) of the 225 participants included in the analysis were found to have acute ZIKV infection. Pregnancy and reports of previous arboviral infection were associated with a higher risk of ZIKV infection. Rash, conjunctivitis, sore throat, and lower absolute neutrophil counts were associated with acute ZIKV infection. The clinical characteristics and risk factors identified were consistent with those identified by previous studies; however, we found sore throat to be a feature of ZIKV infection. We also found that neutrophil counts were lower in ZIKV-infected subjects. These clinical symptoms and laboratory data may help clinicians suspect ZIKV infection during future outbreaks.

Immunoreactivity of Sera From Low to Moderate Malaria-Endemic Areas Against Plasmodium vivax rPvs48/45 Proteins Produced in Escherichia coli and Chinese Hamster Ovary Systems.

P48/45 is a conserved gametocyte antigen involved in Plasmodium parasite fertilization. A recombinant Plasmodium vivax P48/45 (Pvs48/45) protein expressed in Escherichia coli (E. coli) was highly antigenic and immunogenic in experimental animals and elicited specific transmission-blocking (TB) antibodies in a previous pilot study. Here, a similar Pvs48/45 gene was expressed in Chinese Hamster Ovary (CHO) cells and we compared its immunoreactivity with the E. coli product. Specific antibody titers were determined using plasma from Colombian individuals (n=227) living in endemic areas where both P. vivax and P. falciparum are prevalent and from Guatemala (n=54) where P. vivax is highly prevalent. In Colombia, plasma seroprevalence to CHO-rPvs48/45 protein was 46.3%, while for E. coli-rPvs48/45 protein was 36.1% (p<0.001). In Guatemala, the sero prevalence was 24.1% and 14.8% (p<0.001), respectively. Reactivity index (RI) against both proteins showed an age-dependent increase. IgG2 was the predominant subclass and the antibody avidity index evaluated by ELISA ranged between 4-6 mol/L. Ex vivo P. vivax mosquito direct membrane feeding assays (DMFA) performed in presence of study plasmas, displayed significant parasite transmission-blocking (TB), however, there was no direct correlation between antibody titers and oocysts transmission reduction activity (%TRA). Nevertheless, DMFA with CHO rPvs48/45 affinity purified IgG showed a dose response; 90.2% TRA at 100 µg/mL and 71.8% inhibition at 10 µg/mL. In conclusion, the CHO-rPvs48/45 protein was more immunoreactive in most of the malaria endemic places studied, and CHO-rPvs48/45 specific IgG showed functional activity, supporting further testing of the protein vaccine potential.

PD-L1 Blockade During Allergen Sensitization Inhibits the Synthesis of Specific Antibodies and Decreases Mast Cell Activation in a Murine Model of Active Cutaneous Anaphylaxis.

Programmed cell death ligand 1(PDL-1) is known for its inhibitory effect on the cellular immune response. Even though it is expressed on the surface of mast cells, its role in allergic diseases is unknown. We analyzed the effects of PD-L1 blockade in a murine model of active cutaneous anaphylaxis (ACA). C57BL/6 mice were sensitized and challenged with ovalbumin (OVA). Blood samples were collected to measure specific immunoglobulins. The mice were divided into six groups that underwent the active cutaneous anaphylaxis procedure. Group 1 (negative control) received 50 µl of phosphate-buffered saline (PBS) subcutaneously, and the other five groups were sensitized with 50 µg of OVA subcutaneously. Group 2 was the positive control, and the others received the anti-PD-L1 antibody or its isotype during sensitization (groups 3 and 4) or during the challenge (groups 5 and 6). All animals that underwent ACA on the ears with OVA and PBS were sacrificed, and the reaction was evaluated by extravasation of Evans blue (measured by spectrophotometry) and histological analysis of the collected fragments. Anti-PD-L1 blockade during the sensitization phase led to a reduction in specific IgE and IgG1 levels, allergic reaction intensity at the ACA site, and mast cell degranulation in the tissue. There was no significant biological effect of anti-PD-L1 administration on the challenge phase. PD-L1 blockade during allergen sensitization inhibited the synthesis of specific IgE and IgG1 and decreased mast cell activation in this murine model of anaphylaxis.

Recombinant antibody against Trypanosoma cruzi from patients with chronic Chagas heart disease recognizes mammalian nervous system.

BACKGROUND: To deeply understand the role of antibodies in the context of Trypanosoma cruzi infection, we decided to characterize A2R1, a parasite antibody selected from single-chain variable fragment (scFv) phage display libraries constructed from B cells of chronic Chagas heart disease patients. METHODS: Immunoblot, ELISA, cytometry, immunofluorescence and immunohistochemical assays were used to characterize A2R1 reactivity. To identify the antibody target, we performed an immunoprecipitation and two-dimensional electrophoresis coupled to mass spectrometry and confirmed A2R1 specific interaction by producing the antigen in different expression systems. Based on these data, we carried out a comparative in silico analysis of the protein target´s orthologues, focusing mainly on post-translational modifications. FINDINGS: A2R1 recognizes a parasite protein of ~50 kDa present in all life cycle stages of T. cruzi, as well as in other members of the kinetoplastid family, showing a defined immunofluorescence labeling pattern consistent with the cytoskeleton. A2R1 binds to tubulin, but this interaction relies on its post-translational modifications. Interestingly, this antibody also targets mammalian tubulin only present in brain, staining in and around cell bodies of the human peripheral and central nervous system. INTERPRETATION: Our findings demonstrate for the first time the existence of a human antibody against T. cruzi tubulin capable of cross-reacting with a human neural protein. This work re-emphasizes the role of molecular mimicry between host and parasitic antigens in the development of pathological manifestations of T. cruzi infection.

Specificities and isotypes of erythrocytes autoantibodies in patients with warm autoimmune hemolytic anemia / Especificidades e isotipos de autoanticuerpos eritrocitarios en pacientes con anemia hemolítica autoinmune caliente

Introduction: Autoimmune hemolytic anemia is a rare disorder characterized by hemolysis mediated by autoantibodies directed against red blood cells. The demonstration of antibody specificity is a very difficult procedure since autoantibodies in general are nonspecific of antigens and react with all erythrocytes analyzed. Occasionally, specificity is observed against the Rh system antigens. Objective: To determinate the specificity of erythrocytes autoantibodies in DAT positive autoimmune hemolytic anemia by MAIEA technique. Methods: The specificity and isotype of erythrocyte autoantibodies were determined in the eluate of 109 blood samples from patients with warm autoimmune hemolytic anemia, by means of the MAIEA technique and the use of monoclonal antibodies that recognized 11 blood group systems and the protein CD47. Results: In 100 percent of cases autoantibodies against Rh system antigens were detected; in 24 cases we detected autoantibodies of IgA and IgM isotypes that recognized different antigens that were recognized by IgG isotype autoantibodies. For idiopathic and secondary warm autoimmune hemolytic anemias, predominance was observed against three or more specificities. IgG was detected in 99.09 percent of the eluates, IgA in 35.77 percent and IgM in 16.51 percent. The high degree of hemolysis was related to the presence of several isotype autoantibodies against four or more blood group specificities. Conclusions: The MAIEA technique is a sensitive method that can be used to determine the specificities and isotypes of autoantibodies in patients with warm autoimmune hemolytic anemia.

Introducción: La anemia hemolítica autoinmune es un trastorno poco común, caracterizado por hemólisis mediada por autoanticuerpos dirigidos contra los glóbulos rojos. La demostración de la especificidad de los anticuerpos es un procedimiento muy difícil, ya que los autoanticuerpos en general no son específicos de los antígenos y reaccionan con todos los eritrocitos analizados. Ocasionalmente, se observa especificidad contra los antígenos del sistema Rh. Objetivo: Determinar la especificidad de los autoanticuerpos eritrocitarios en pacientes con anemias hemolíticas autoinmunes PAD positivas con el empleo de la técnica MAIEA Métodos: Se determinó la especificidad e isotipo de los autoanticuerpos eritrocitarios en el eluido de 109 muestras de sangre de pacientes con anemia hemolítica autoinmune caliente, mediante la técnica de MAIEA y el uso de anticuerpos monoclonales que reconocieron 11 sistemas de grupos sanguíneos y la proteína CD47. Resultados: En el ciento por ciento de los casos se detectaron autoanticuerpos contra los antígenos del sistema Rh. En 24 casos se descubrió autoanticuerpos de isotipos IgA e IgM que reconocieron diferentes antígenos que fueron a su vez reconocidos por autoanticuerpos de isotipo IgG. Se observó para las anemias hemolíticas autoinmunes calientes idiopáticas y secundarias; predominio frente a tres o más especificidades. Se detectó IgG en el 99,09 por ciento de los eluidos, IgA en 35,77 por ciento e IgM en 16,51 por ciento. El alto grado de hemólisis se relacionó con la presencia de varios isotipos de autoanticuerpos contra cuatro o más especificidades de grupos sanguíneos. Conclusiones: La técnica MAIEA es un método sensible que puede usarse para determinar las especificidades e isotipos de autoanticuerpos en pacientes con anemia hemolítica autoinmune caliente.

Immunological follow-up of patients with renal transplants: A proposal for clinical practice in Colombia / Seguimiento inmunológico después de trasplante renal: una propuesta para la práctica clínica en Colombia.

Graft damage is a process that starts at the moment of transplantation, due to comorbidities of receptor, donor status, ischemia time, ischemia-reperfusion phenomenon, among others, those induce metabolic and immune factors that ultimately trigger clinical manifestations of graft dysfunction. However, the preclinical progression between the time of transplantation and the appearance of signs and symptoms of graft damage can take weeks to years. Therefore, the implementation of rational monitoring approaches during the post-transplantation period is critical and should include not only the clinical follow-up but also anticipate immunological graft damage. In the present essay, we propose an immunological monitoring algorithm for the post-renal transplantation period.

El daño del injerto es un proceso multifactorial que se inicia tempranamente después de la mayoría de los trasplantes de donantes sin HLA idéntico. Puede deberse a las comorbilidades del receptor, al estado del donante, al tiempo de isquemia, y al fenómeno de isquemia y reperfusión, entre otros, condiciones que inducen factores metabólicos e inmunológicos que finalmente desembocan en la disfunción del injerto. Sin embargo, entre el momento del trasplante y la aparición de los signos y síntomas existe un periodo que puede tardar semanas o años. Por ello, después del trasplante renal, es importante hacer un seguimiento racional que incluya la evaluación clínica y permita anticiparse al daño inmunológico del injerto. En este ensayo se propone un algoritmo de seguimiento del injerto renal después del trasplante.

Cross-Reactive Carbohydrate Determinant in Apis mellifera, Solenopsis invicta and Polybia paulista Venoms: Identification of Allergic Sensitization and Cross-Reactivity.

Allergic reactions to Hymenoptera venom, which could lead to systemic and even fatal symptoms, is characterized by hypersensitivity reactions mediated by specific IgE (sIgE) driven to venom allergens. Patients multisensitized to sIgE usually recognize more than one allergen in different Hymenoptera species. However, the presence of sIgE directed against Cross-Reactive Carbohydrate Determinant (CCD), which occurs in some allergens from Hymenoptera venom, hampers the identification of the culprit insects. CCD is also present in plants, pollen, fruits, but not in mammals. Bromelain (Brl) extracted from pineapples is a glycoprotein commonly used for reference to sIgE-CCD detection and analysis. In sera of fifty-one Hymenoptera allergic patients with specific IgE ≥ 1.0 KU/L, we assessed by immunoblotting the reactivity of sIgE to the major allergens of Apis mellifera, Polybia paulista and Solenopsis invicta venoms. We also distinguished, using sera adsorption procedures, the cases of CCD cross-reaction using Brl as a marker and inhibitor of CCD epitopes. The presence of reactivity for bromelain (24-28 kDa) was obtained in 43% of the patients, in which 64% presented reactivity for more than one Hymenoptera venom in radioallergosorbent (RAST) tests, and 90% showed reactivity in immunoblot analysis to the major allergens of Apis mellifera, Polybia paulista and Solenopsis invicta venoms. Sera adsorption procedures with Brl lead to a significant reduction in patients' sera reactivity to the Hymenoptera allergens. Immunoblotting assay using pre- and post-Brl adsorption sera from wasp-allergic patients blotted with non-glycosylated recombinant antigens (rPoly p1, rPoly p5) from Polybia paulista wasp venom showed no change in reactivity pattern of sIgE that recognize allergen peptide epitopes. Our results, using Brl as a marker and CCD inhibitor to test sIgE reactivity, suggest that it could complement diagnostic methods and help to differentiate specific reactivity to allergens' peptide epitopes from cross-reactivity caused by CCD, which is extremely useful in clinical practice.

[Isolated area postrema syndrome with anti-MOG antibodies, a rare association]. / Síndrome del área postrema aislado con anticuerpos anti-MOG, una asociación poco frecuente.

TITLE: Síndrome del área postrema aislado con anticuerpos anti-MOG, una asociación poco frecuente.

Renal transplant patients with preformed anti-HLA antibodies: early biopsy findings and clinical outcomes / Pacientes transplantados renais com anticorpos anti-HLA pré-formados: achados precoces de biópsia e desfechos clínicos

Abstract Introduction: Renal fibrosis is the end point of a process that begins at transplant, with ischemia reperfusion and early inflammation, and progresses over time with immunological and non-immunological phenomena. Early identification of morphological markers and intervention could improve graft function and survival. Objective: to evaluate the correlation between intensity and specificity of pre-transplant anti-HLA antibodies and kidney allograft pathology in order to identify early risk factors or markers of allograft dysfunction. Methods: A retrospective cohort of kidney transplant recipients with pre-transplant anti-HLA antibodies who underwent graft biopsy within the first two years post-transplant was divided into two groups according to the specificity of anti-HLA antibodies: nonspecific (non-DSA, n = 29) and specific (DSA+, n = 16). Kidney graft pathology, renal function, and proteinuria were analyzed. Results: general characteristics were similar in both groups, except for the higher dose of thymoglobulin in DSA+ group (p < 0.05). The non-DSA group had higher scores for glomerulosclerosis, interstitial inflammation (i) and interstitial fibrosis (ci) (p < 0.05) and higher incidence of cell-mediated acute rejection. No statistical difference in incidence of antibody-mediated rejection, renal function, and proteinuria was observed during follow up. Discussion and conclusions: the difference in inflammation scores and interstitial fibrosis may be associated to the higher incidence of acute cell-mediated rejection and polyomavirus nephropathy in the Non-DSA group. We also should take into account the protective effect of higher doses of thymoglobulin, reducing ischemia reperfusion injury in the DSA+ group. The short follow-up might have been insufficient to detect long-term changes in allograft tissue, renal function, and proteinuria.

Resumo Introdução: A fibrose renal é o desfecho de um processo iniciado no transplante, com reperfusão, isquemia e inflamação precoce, que progride ao longo do tempo com fenômenos imunológicos e não imunológicos. A identificação de marcadores morfológicos e a intervenção precoce poderiam melhorar a função e a sobrevida do enxerto. Objetivo: Avaliar a correlação entre intensidade e especificidade de anticorpos anti-HLA pré-transplante alterações histológicas do enxerto renal, de forma a identificar fatores de risco ou marcadores de disfunção precoces do aloenxerto. Métodos: O presente estudo incluiu uma coorte retrospectiva de receptores de transplante renal sensibilizados com anticorpos anti-HLA no pré-transplante submetidos a biópsia de enxerto nos primeiros dois anos após o transplante. Os grupos foram divididos em função da especificidade dos anticorpos anti-HLA: sem anticorpos doador-específicos (não-DSA, n = 29) e com anticorpos doador-específicos (DSA+, n = 16). Alterações histológicas do enxerto renal, função renal e proteinúria foram analisados. Resultados: Os dois grupos tinham características gerais semelhantes, exceto pela dose mais elevada de timoglobulina administrada nos indivíduos do grupo DSA+ (p < 0,05). O grupo não-DSA teve escores mais elevados de glomeruloesclerose, inflamação intersticial (i) e fibrose intersticial (ci) (p < 0,05), além de maior incidência de rejeição celular aguda (RCA). Não foi observada diferença estatística na incidência de rejeição mediada por anticorpos, função renal ou proteinúria durante o seguimento. Discussão e Conclusões: A diferença nos escores de inflamação e fibrose intersticial pode estar associada à maior incidência de RCA e nefropatia por poliomavírus no grupo não-DSA. Devemos considerar ainda o efeito protetor das doses mais elevadas de timoglobulina na redução da lesão por isquemia-reperfusão no grupo DSA+. O curto período de seguimento pode ter sido insuficiente para detectar alterações de longo prazo no tecido do aloenxerto, função renal e proteinúria.

High performance of an enzyme linked immunosorbent assay for American tegumentary leishmaniasis diagnosis with Leishmania (Viannia) braziliensis amastigotes membrane crude antigens.

The diagnosis of American tegumentary leishmaniasis (ATL) still requires the design of more effective tools. Leishmania (Viannia) braziliensis is the causal agent of the 90% of Argentinean ATL cases. Considering the current knowledge, an ELISA based crude antigen (CA) for the diagnosis was designed. Ninety-nine subjects diagnosed as ATL, 27 as no-ATL, and 84 donors from non-ATL-endemic areas were included in this study. The current ATL diagnosis was based four techniques, dermal smear microscopic examination (parasitological test), PCR, Leishmanin skin test, and clinical records. We obtained CA extracts from promastigotes and amastigotes from macrophage cultures of different zymodemes of endemic Leishmania species circulating in the study area. Crude antigens from the 'local' main zymodeme of L. (V.) braziliensis showed the highest reactivity against anti-Leishmania antibodies compared to the other included species. The CA of amastigotes of this zymodeme was 3.4 fold more reactive than promastigotes one. Moreover, amastigote-membrane CA (MCA) were 3.6 fold more reactive than the soluble antigens. The MCA-ELISA reached a sensitivity and specificity of 98% (CI = 94.7%-100%) and 63.6% (53.9-73.1), respectively. When anti-Trypanosoma cruzi reactive sera were excluded, the specificity reached 98.4% (94.4-100), while the sensitivity was similar, with a positive predictive value (PV) of 98.6% (94.6-100) and negative PV of 96.3% (91.6-100). The performance of the MCA-ELISA results strongly contribute to the final diagnostic decision, since a non-reactive serological result almost discards the suspected ATL, because of its high negative PV. The developed MCA-ELISA showed a high diagnostic performance, which makes it a good candidate for ATL diagnosis, for seroprevalence studies, or for monitoring treatments efficacy.

Initial development of biosimilar immune checkpoint blockers using HEK293 cells.

Antibodies that block interaction of immune checkpoint receptors with its ligands have revolutionized the treatment of several cancers. Despite the success of this approach, the high cost has been restricted the use of this class of drugs. In this context, the development of biosimilar can be an important strategy for reducing prices and expanding access after patent has been dropped. Here, we evaluated the use of HEK293 cells for transient expression of an immune checkpoint-blocking antibody as a first step for biosimilar development. Antibody light and heavy chain genes were cloned into pCI-neo vector and transiently expressed in HEK293 cells. The culture supernatant was then subjected to protein A affinity chromatography, which allowed to obtain the antibody with high homogeneity. For physicochemical comparability, biosimilar antibody and reference drug were analyzed by SDS-PAGE, isoelectric focusing, circular dichroism and fluorescence spectroscopy. The results indicated that the both antibodies have a high degree of structural similarity. Lastly, the biosimilar antibody binding capacity to target receptor was shown to be similar to reference product in ELISA and flow cytometry assays. These data demonstrate that the HEK293 system can be used as an important tool for candidate selection and early development of biosimilar antibodies.

Quality control of multiplex antibody detection in samples from large-scale surveys: the example of malaria in Haiti.

Measuring antimalarial antibodies can estimate transmission in a population. To compare outputs, standardized laboratory testing is required. Here we describe the in-country establishment and quality control (QC) of a multiplex bead assay (MBA) for three sero-surveys in Haiti. Total IgG data against 21 antigens were collected for 32,758 participants. Titration curves of hyperimmune sera were included on assay plates, assay signals underwent 5-parameter regression, and inspection of the median and interquartile range (IQR) for the y-inflection point was used to determine assay precision. The medians and IQRs were similar for Surveys 1 and 2 for most antigens, while the IQRs increased for some antigens in Survey 3. Levey-Jennings charts for selected antigens provided a pass/fail criterion for each assay plate and, of 387 assay plates, 13 (3.4%) were repeated. Individual samples failed if IgG binding to the generic glutathione-S-transferase protein was observed, with 659 (2.0%) samples failing. An additional 455 (1.4%) observations failed due to low bead numbers (<20/analyte). The final dataset included 609,438 anti-malaria IgG data points from 32,099 participants; 96.6% of all potential data points if no QC failures had occurred. The MBA can be deployed with high-throughput data collection and low inter-plate variability while ensuring data quality.

Multipathogen Analysis of IgA and IgG Antigen Specificity for Selected Pathogens in Milk Produced by Women From Diverse Geographical Regions: The INSPIRE Study.

Breastfeeding provides defense against infectious disease during early life. The mechanisms underlying this protection are complex but likely include the vast array of immune cells and components, such as immunoglobulins, in milk. Simply characterizing the concentrations of these bioactives, however, provides only limited information regarding their potential relationships with disease risk in the recipient infant. Rather, understanding pathogen and antigen specificity profiles of milk-borne immunoglobulins might lead to a more complete understanding of how maternal immunity impacts infant health and wellbeing. Milk produced by women living in 11 geographically dispersed populations was applied to a protein microarray containing antigens from 16 pathogens, including diarrheagenic E. coli, Shigella spp., Salmonella enterica serovar Typhi, Staphylococcus aureus, Streptococcus pneumoniae, Mycobacterium tuberculosis and other pathogens of global health concern, and specific IgA and IgG binding was measured. Our analysis identified novel disease-specific antigen responses and suggests that some IgA and IgG responses vary substantially within and among populations. Patterns of antibody reactivity analyzed by principal component analysis and differential reactivity analysis were associated with either lower-to-middle-income countries (LMICs) or high-income countries (HICs). Antibody levels were generally higher in LMICs than HICs, particularly for Shigella and diarrheagenic E. coli antigens, although sets of S. aureus, S. pneumoniae, and some M. tuberculosis antigens were more reactive in HICs. Differential responses were typically specific to canonical immunodominant antigens, but a set of nondifferential but highly reactive antibodies were specific to antigens possibly universally recognized by antibodies in human milk. This approach provides a promising means to understand how breastfeeding and human milk protect (or do not protect) infants from environmentally relevant pathogens. Furthermore, this approach might lead to interventions to boost population-specific immunity in at-risk breastfeeding mothers and their infants.

A highly specific and sensitive nanoimmunosensor for the diagnosis of neuromyelitis optica spectrum disorders.

A precise diagnosis for neuromyelitis optica spectrum disorders (NMOSD) is crucial to improve patients' prognostic, which requires highly specific and sensitive tests. The cell-based assay with a sensitivity of 76% and specificity of 100% is the most recommended test to detect anti-aquaporin-4 antibodies (AQP4-Ab). Here, we tested four AQP4 external loop peptides (AQP461-70, AQP4131-140, AQP4141-150, and AQP4201-210) with an atomic force microscopy nanoimmunosensor to develop a diagnostic assay. We obtained the highest reactivity with AQP461-70-nanoimunosensor. This assay was effective in detecting AQP4-Ab in sera of NMOSD patients with 100% specificity (95% CI 63.06-100), determined by the cut-off adhesion force value of 241.3 pN. NMOSD patients were successfully discriminated from a set of healthy volunteers, patients with multiple sclerosis, and AQP4-Ab-negative patients. AQP461-70 sensitivity was 81.25% (95% CI 56.50-99.43), slightly higher than with the CBA method. The results with the AQP461-70-nanoimmunosensor indicate that the differences between NMOSD seropositive and seronegative phenotypes are related to disease-specific epitopes. The absence of AQP4-Ab in sera of NMOSD AQP4-Ab-negative patients may be interpreted by assuming the existence of another potential AQP4 peptide sequence or non-AQP4 antigens as the antibody target.

Renal transplant patients with preformed anti-HLA antibodies: early biopsy findings and clinical outcomes.

INTRODUCTION: Renal fibrosis is the end point of a process that begins at transplant, with ischemia reperfusion and early inflammation, and progresses over time with immunological and non-immunological phenomena. Early identification of morphological markers and intervention could improve graft function and survival. OBJECTIVE: to evaluate the correlation between intensity and specificity of pre-transplant anti-HLA antibodies and kidney allograft pathology in order to identify early risk factors or markers of allograft dysfunction. METHODS: A retrospective cohort of kidney transplant recipients with pre-transplant anti-HLA antibodies who underwent graft biopsy within the first two years post-transplant was divided into two groups according to the specificity of anti-HLA antibodies: nonspecific (non-DSA, n = 29) and specific (DSA+, n = 16). Kidney graft pathology, renal function, and proteinuria were analyzed. RESULTS: general characteristics were similar in both groups, except for the higher dose of thymoglobulin in DSA+ group (p < 0.05). The non-DSA group had higher scores for glomerulosclerosis, interstitial inflammation (i) and interstitial fibrosis (ci) (p < 0.05) and higher incidence of cell-mediated acute rejection. No statistical difference in incidence of antibody-mediated rejection, renal function, and proteinuria was observed during follow up. DISCUSSION AND CONCLUSIONS: the difference in inflammation scores and interstitial fibrosis may be associated to the higher incidence of acute cell-mediated rejection and polyomavirus nephropathy in the Non-DSA group. We also should take into account the protective effect of higher doses of thymoglobulin, reducing ischemia reperfusion injury in the DSA+ group. The short follow-up might have been insufficient to detect long-term changes in allograft tissue, renal function, and proteinuria.

Prevalence and laboratorial determinants of the clinical relevance of antibodies of undetermined specificity.

BACKGROUND AND OBJECTIVES: Antibodies of unknown specificity (AUS) are frequently identified in the pre-transfusion testing. These antibodies can be insignificant or potentially cause post-transfusion haemolysis. Information about the prevalence of clinically relevant AUS is still lacking. Our aim was to predict the potential clinical relevance of AUS using the monocyte monolayer assay (MMA) and to identify the clinical and laboratorial determinants of AUS' significance. MATERIALS AND METHODS: Antibodies of unknown specificity identified at a single institution from 2015-2017 were evaluated through MMA. A monocyte index (MI) of more than 5% was predictive of potential post-transfusion haemolysis. RESULTS: Thirty-two patients with AUS were included in the study. Of the studied AUS, 37·5% (12/32) presented with a monocyte index (MI) more than 5%. In the group of significant AUS, 41·7% of the patients presented with sickle cell disease (SCD) and the AUS were associated with Rh antibodies in 75% of the cases. In the group of insignificant AUS, only 10% of the patients had SCD and the association with Rh antibodies was detected in 20% of the cases. The presence of Rh antibodies was independently associated with the AUS clinical relevance (P = 0·012). CONCLUSION: More than one-third of the AUS are potentially clinically relevant, and the association with Rh antibodies is predictive of AUS relevance. Services must honour AUS in the pre-transfusion process in order to ensure transfusion safety.