Computational Tools for the Identification and Interpretation of Sequence Motifs in Immunopeptidomes.

Recent advances in proteomics and mass-spectrometry have widely expanded the detectable peptide repertoire presented by major histocompatibility complex (MHC) molecules on the cell surface, collectively known as the immunopeptidome. Finely characterizing the immunopeptidome brings about important basic insights into the mechanisms of antigen presentation, but can also reveal promising targets for vaccine development and cancer immunotherapy. This report describes a number of practical and efficient approaches to analyze immunopeptidomics data, discussing the identification of meaningful sequence motifs in various scenarios and considering current limitations. Guidelines are provided for the filtering of false hits and contaminants, and to address the problem of motif deconvolution in cell lines expressing multiple MHC alleles, both for the MHC class I and class II systems. Finally, it is demonstrated how machine learning can be readily employed by non-expert users to generate accurate prediction models directly from mass-spectrometry eluted ligand data sets.

The Emerging Role of the Major Histocompatibility Complex Class I in Amyotrophic Lateral Sclerosis.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease affecting upper and lower motoneurons (MNs). The etiology of the disease is still unknown for most patients with sporadic ALS, while in 5-10% of the familial cases, several gene mutations have been linked to the disease. Mutations in the gene encoding Cu, Zn superoxide dismutase (SOD1), reproducing in animal models a pathological scenario similar to that found in ALS patients, have allowed for the identification of mechanisms relevant to the ALS pathogenesis. Among them, neuroinflammation mediated by glial cells and systemic immune activation play a key role in the progression of the disease, through mechanisms that can be either neuroprotective or neurodetrimental depending on the type of cells and the MN compartment involved. In this review, we will examine and discuss the involvement of major histocompatibility complex class I (MHCI) in ALS concerning its function in the adaptive immunity and its role in modulating the neural plasticity in the central and peripheral nervous system. The evidence indicates that the overexpression of MHCI into MNs protect them from astrocytes' toxicity in the central nervous system (CNS) and promote the removal of degenerating motor axons accelerating collateral reinnervation of muscles.

Expressão de antígenos MHC classe I e de células CD4 e CD8 na polimiosite e dermatomiosite / MHC class I antigens, CD4 and CD8 expressions in polymyositis and dermatomyositis

Objetivo: Analisar as frequências de expressão dos antígenos de complexo principal de histocompatibilidade classe I (MHC-I) e células CD4 e CD8 no músculo esquelético na polimiosite (PM) e dermatomiosite (DM). Métodos: Estudo retrospectivo de 34 casos de PM, oito casos de DM e 29 controles com miopatias não inflamatórias. Resultados: Os antígenos MHC-I expressaram-se no sarcolema e/ou sarcoplasma em 79,4% dos casos de PM, 62,5% dos casos de DM e 27,6% dos controles (a expressão de CD4 foi observada em 76,5%, 75% e 13,8%, respectivamente). Quando os antígenos de MHC-I foram coexpressados com CD4, houve elevada suspeita de PM/DM (principalmente PM). Em 14,3% dos casos de PM/DM, observou-se a expressão isolada dos antígenos MHC-I, sem células inflamatórias. Conclusão: A expressão dos antígenos MHC-I e a positividade do CD4 podem aumentar a suspeita diagnóstica de PM/DM. Não foi observado infiltrado celular em 14,3% dos casos. .

Objective: To analyze the frequencies of the expression of major histocompatibility complex class I (MHC-I) antigens, and CD4 and CD8 cells in skeletal muscle in polymyositis (PM) and dermatomyositis (DM). Methods: This was a retrospective study of 34 PM cases, 8 DM cases, and 29 control patients with non-inflammatory myopathies. Results: MHC-I antigens were expressed in the sarcolemma and/or sarcoplasm in 79.4% of PM cases, 62.5% of DM cases, and 27.6% of controls (CD4 expression was observed in 76.5%, 75%, and 13.8%, respectively). There was a high suspicion of PM/DM (mainly PM) in participants in whom MHC-I antigens and CD4 were co-expressed. In 14.3% of PM/DM cases, we observed MHC-I antigens expression alone, without inflammatory cells. Conclusion: MHC-I antigens expression and CD4 positivity might add to strong diagnostic suspicion of PM/DM. No cellular infiltration was observed in approximately 14.3% of such cases. .

[MHC class I antigens, CD4 and CD8 expressions in polymyositis and dermatomyositis]. / Expressão de antígenos MHC classe I e de células CD4 e CD8 na polimiosite e dermatomiosite.

OBJECTIVE: To analyze the frequencies of the expression of major histocompatibility complex class I (MHC-I) antigens, and CD4 and CD8 cells in skeletal muscle in polymyositis (PM) and dermatomyositis (DM). METHODS: This was a retrospective study of 34 PM cases, 8 DM cases, and 29 control patients with non-inflammatory myopathies. RESULTS: MHC-I antigens were expressed in the sarcolemma and/or sarcoplasm in 79.4% of PM cases, 62.5% of DM cases, and 27.6% of controls (CD4 expression was observed in 76.5%, 75%, and 13.8%, respectively). There was a high suspicion of PM/DM (mainly PM) in patients in whom MHC-I antigens and CD4 were co-expressed. In 14.3% of PM/DM cases, we observed MHC-I antigens expression alone, without inflammatory cells. CONCLUSION: MCH-I antigens expression and CD4 positivity might add to strong diagnostic suspicion of PM/DM. No cellular infiltration was observed in 14.3% of such cases.

Differential expression of immune-modulatory molecule HLA-E in non-neoplastic and neoplastic lesions of the thyroid.

Human leukocyte antigen (HLA)–E is a non-classical molecule of the histocompatibility complex that functions as one of the main ligands of the Natural Killer (NK) cell inhibitory receptor CD94/NKG2A and inhibits its potent cytotoxic activity. Due to the important role of NK cells in combating neoplasm, we hypothesized that the differential expression of HLA-E could favor the progression of heterogeneous thyroid tumors.Using an immunohistochemistry technique in 143 biopsies of thyroid tumors, including benign and malignant neoplasms and goiters, we evaluated the expression of HLA-E among various tumor types and its association with the clinicopathological factors of diseases. We verified high HLA-E expression in all types of neoplastic tumors, although no significant differences between the groups were found. Low expression was observed in 95 percent of the goiter samples, showing significant differences between neoplastic and non-neoplastic lesions. Furthermore, a significant result was found with regard to the tumor size, with high HLA-E expression being related to smaller tumors. Therefore, our data suggest that an increase in HLA-E may be associated with the establishment of thyroid neoplasms, with either benign or malignant features.

Morphometric analyses of normal pediatric brachial biceps and quadriceps muscle tissue.

Pediatric normal brachial biceps (14 specimens) and quadriceps muscles (14 specimens) were studied by immunohistochemistry to quantify fiber-type, diameter and distribution, capillary density, presence of inflammatory cells (CD3, CD20, CD68) and expression of neonatal myosin and MHC class 1 proteins. Brachial biceps showed more fast-twitch fibers and lower capillary/fiber ratio than quadriceps. The mean diameter of both fiber types was smaller in biceps than quadriceps. Fast-fibers were smaller than slow-fibers, and capillary/fiber ratio was < 1.0 in both muscles. Fiber size and capillary / fiber ratio increased with age. Normal limits for infiltrating haematopoietic cells were <4 T lymphocytes, or CD68+ cells, very few B cells, < 6 neonatal myosin positive fibers, and no fibers MHC class 1 positive in one x20 field, for both muscles. The present comparison of quantitative findings between brachial biceps and quadriceps may allow standardization of the assessment of pathological changes in both pediatric muscles.

HLA among Brazilian patients with spontaneous chronic urticaria and positive autologous serum skin test.

BACKGROUND: An association between class I and II alleles of the major histocompatibility complex and idiopathic chronic urticaria has previously been observed in different populations, but there are still no studies on Brazilian populations in this regard. OBJECTIVE: The involvement of the major histocompatibility complex classes I and II (loci A, B and DR) in Brazilian patients with idiopathic chronic urticaria and a positive autologous serum skin test was investigated and compared with a healthy population group. METHODS: DNA was extracted from the blood of 42 patients with idiopathic chronic urticaria and major histocompatibility complex classes I and II alleles were determined using the polymerase chain reaction and a laboratory test for oligonucleotide hybridization using a single-filament probe. The frequencies of these alleles in patients with chronic urticaria were compared with the frequencies in 1000 genetically unrelated voluntary blood donors from the same region of Brazil. The diagnosis of idiopathic chronic urticaria was based on the patients' clinical history and routine laboratory tests. Only the patients with positive autologous serum skin test were selected. The allele distribution resulted from the patient and control groups were analyzed using odds ratios and 95% confidence intervals. RESULTS: No statistically significant differences were found between the positive autologous serum skin test patients with chronic urticaria and the control group. CONCLUSIONS: We found that in this population group, there was no specific association between the HLA alleles studied and chronic urticaria. We believe that further population studies are needed in order to investigate the possible existence of this association.

HLA among Brazilian patients with spontaneous chronic urticaria and positive autologous serum skin test / HLA em brasileiros com urticária crônica espontânea e teste cutâneo do soro autólogo positivo

BACKGROUND: An association between class I and II alleles of the major histocompatibility complex and idiopathic chronic urticaria has previously been observed in different populations, but there are still no studies on Brazilian populations in this regard. OBJECTIVE: The involvement of the major histocompatibility complex classes I and II (loci A, B and DR) in Brazilian patients with idiopathic chronic urticaria and a positive autologous serum skin test was investigated and compared with a healthy population group. METHODS: DNA was extracted from the blood of 42 patients with idiopathic chronic urticaria and major histocompatibility complex classes I and II alleles were determined using the polymerase chain reaction and a laboratory test for oligonucleotide hybridization using a single-filament probe. The frequencies of these alleles in patients with chronic urticaria were compared with the frequencies in 1000 genetically unrelated voluntary blood donors from the same region of Brazil. The diagnosis of idiopathic chronic urticaria was based on the patients' clinical history and routine laboratory tests. Only the patients with positive autologous serum skin test were selected. The allele distribution resulted from the patient and control groups were analyzed using odds ratios and 95% confidence intervals. RESULTS: No statistically significant differences were found between the positive autologous serum skin test patients with chronic urticaria and the control group. CONCLUSIONS: We found that in this population group, there was no specific association between the HLA alleles studied and chronic urticaria. We believe that further population studies are needed in order to investigate the possible existence of this association.

FUNDAMENTOS: A associação entre os alelos do MHC classe I e II e a urticária crônica idiopática tem sido previamente constatada em diferentes populações, sendo que na população brasileira ainda não existem estudos a este respeito. OBJETIVOS: Foi estudado o envolvimento do MHC classe I e II (locci A, B e DR) em pacientes brasileiros com urticária crônica idiopática e teste cutâneo do soro autólogo positivo, comparando-se com um grupo populacional saudável. MÉTODOS: O DNA foi extraído do sangue de 42 pacientes com urticária crônica idiopática e o MHC classe I e II determinado por reação em cadeia da polimerase e teste laboratorial de hibridização de oligonucleotídeo com sonda de filamento único. A freqüência destes alelos em pacientes com urticária crônica idiopática foi comparada com a de 1000 doadores de sangue voluntários e geneticamente não relacionados, da mesma região do Brasil. O diagnóstico de urticária crônica idiopática foi baseado na história clínica do paciente e exames laboratoriais de rotina; foram selecionados apenas os pacientes com teste cutâneo do soro autólogo positivo. O resultado da distribuição alélica entre o grupo de pacientes e o grupo controle foi analisado através do odds rate com o cálculo do intervalo de confiança de 95% (95% IC). RESULTADOS: Não foram encontradas diferenças com significância estatística entre os pacientes com urticária crônica teste cutâneo do soro autólogo positivos e o grupo controle. CONCLUSÕES: Verificamos que neste grupo populacional estudado não houve associação específica entre os alelos HLA estudados e a urticária crônica; acreditamos na necessidade de outros estudos populacionais, para podermos verificar a possível existência desta associação.

Expression of the nonclassical HLA-G and HLA-E molecules in laryngeal lesions as biomarkers of tumor invasiveness.

INTRODUCTION: HLA-G and HLA-E are two nonclassical class I molecules, which have been well recognized as modulators of innate and adaptive immune responses, and the expression of these molecules in virus infected cells has been associated with subversion of the immune response. OBJECTIVE: In this study we performed a cross-sectional study, systematically comparing the expression of HLA-G and HLA-E in benign, pre-malignant and malignant laryngeal lesions, correlating with demographic and clinical variables and with the presence of high-risk and low-risk HPV types. MATERIALS AND METHODS: Laryngeal lesions were collected from 109 patients and stratified into 27 laryngeal papillomas, 17 dysplasias, 10 in situ laryngeal carcinomas, 27 laryngeal carcinomas without metastases, 28 laryngeal carcinomas with metastasis along with their respective draining cervical lymph nodes, and 10 normal larynx specimens. The expression of HLA-G and HLA-E molecules was determined by immunohistochemistry. HPV DNA detection and typing was performed using generic and specific primers. RESULTS: HLA nonclassical molecules showed a distinct distribution pattern, according to the larynx lesion grade. HLA-G expression increased in benign and premalignant lesions, and gradually decreased in invasive carcinomas and in respective draining cervical lymph nodes. Conversely, HLA-E expression increased as far as lesion grade increased, including increased molecule expression in the draining lymph nodes of malignant lesions. Only 17 (15.6%) patients were HPV DNA positive. CONCLUSIONS: Overexpression of HLA-E and underexpression of HLA-G appear to be good markers for malignant larynx lesion.

The nucleoporin Nup96 is required for proper expression of interferon-regulated proteins and functions.

Nup98 and Nup96 are components of the nuclear transport machinery and are induced by interferons (IFN). Nup98 is a constituent of an mRNA export pathway that is targeted by viruses and regulated by IFN. However, the role of Nup96 in IFN-related mechanisms has not been established. To investigate the function of Nup96 in vivo, we generated Nup96(+/-) mice that express low levels of Nup96, as Nup96(-/-) mice are lethal. The Nup96(+/-) mice presented selective alterations of the immune system, which resulted in downregulation and impaired IFN alpha- and gamma-mediated induction of MHC I and IFNgamma induction of MHC II, ICAM-1, and other proteins. Frequency of TCRalphabeta+ and CD4+ T cells, which depends on MHC function, is reduced in NUP96(+/-) mice. Upon immunization, Nup96(+/-) mice showed impaired antigen presentation and T cell proliferation. Nup96(+/-) cells and mice were highly susceptible to viral infection, demonstrating a role for Nup96 in innate and adaptive immunity.

Immunological evaluation of patients with recurrent abortion.

In a prospective study, we performed immunological tests in patients with recurrent abortion. Nine couples with two or more fetal losses of no apparent cause were selected as the patient group, and nine volunteer couples with at least two children and without a history of abortion were used as controls. The frequency of major histocompatibility complex (human leukocyte antigens, HLA) antigen sharing was determined by serological methods, antipaternal antibodies by microlymphocytotoxicity, lymphocyte phenotypes (CD4, CD8, CD19, CD16, CD56 and HLA-DR positive cells) by flow cytometry and natural killer (NK) cytotoxicity by (51)Cr release. NK activity was correlated to the degree of HLA-C sharing and to the percentage of CD16+ and CD56+ cells and to progesterone levels measured by radioimmunoassay. No difference in class I or class II HLA antigen sharing was detected between couples with and without recurrent abortion. Antipaternal antibodies were not found in the serum of any woman of the study. A higher absolute number of CD8+ cells (P=0.01) and a trend to increased CD19+ cells (P=0.05) were observed among patients. NK activity did not differ between the two groups when expressed as specific cytotoxicity and it was reduced among patients with recurrent abortion when expressed as lytic units/10(7) cells (P=0.04). There was correlation between NK activity and the percentage of CD16+ and CD56+ cells but not with progesterone levels in patients with recurrent abortion. Our data suggest that an increased NK activity may not play a role in the occurrence of repeated abortion. On the other hand, an increase in circulating CD8+ T cells was observed in patients suggesting that antifetal cytotoxicity in recurrent abortion may be mediated by T cells and not by NK cells.

Interferon-alpha 2b modulation of doxorubicin sensitivity in a multidrug resistant cell line.

We evaluated the effect of interferon-alpha2b as a chemosensitiser on HCT-15 cell line in treatment with doxorubicin. Chemosensitivity was determined by [3H]-thymidine incorporation and tetrazolium assays. The levels of expression of P-glycoprotein, Bcl-2 oncoprotein and HLA-ABC complex, and cell cycle/apoptosis analysis were determined by flow cytometry. Dox 50 ng/ml - IFN alpha 2b 500 IU/ml treatment inhibited cell proliferation (47.2 +/- 1.4%, p < 0.0001; MTT assay: 40.6 +/- 1.2%, p < 0.0001) and augmented the expression of P-170, Bcl-2 and HLA-ABC, while it didn't exert apoptosis, producing a slight G2/M arrest. A concentration of IFN-alpha2b, that by itself is not cytotoxic, can potentiate the efficacy of the anticancer drug. This effect is not due to a down-modulation of P-170. The absence of apoptosis and augmented levels of Bcl-2 expression suggests that this could be one of the mechanisms of drug resistance exerted by these cells.

Further evidence of the role of HLA-DR4 in the genetic susceptibility to actinic prurigo.

BACKGROUND: Actinic prurigo (AP) is triggered by sun exposure. Its prevalence in Mexicans seems to be particularly high, which suggests a genetic susceptibility. OBJECTIVE: Our purpose was to determine the role of major histocompatibility complex (MHC) genes in the genetic susceptibility to AP. METHODS: Fifty-six Mexican Mestizo patients with AP underwent serologic typing for HLA class I and class II antigens. Class II MHC genes were also studied by DNA analysis. Findings in patients were compared with 100 ethnically matched healthy controls. RESULTS: We found that 92.8% of patients with AP were HLA-DR4 positive (corrected p = 0.002; odds ratio [OR] = 10.1). The class I antigens HLA-A28 and HLA-B39 (B16) were also significantly increased (p < or = 0.000001, OR = 20.9 and p = 0.0001, OR = 6.7, respectively) compared with normal controls. Allele-specific oligonucleotide DR4 subtyping showed that 80.7% of HLA-DR4+ patients with AP were also positive for the DRB1*0407 allele. CONCLUSION: These results confirm the role of HLA-DR4 (DRB1*0407) in the genetic susceptibility to AP and raise the possibility of a role for class I MHC antigens HLA-A28 and B16 in Mexican patients.

Immunogenetics of HTLV-I/II and associated diseases.

The ethnic background of human T-lymphotropic virus types I and II (HTLV-I/II) infections and associated diseases was investigated in association with human leukocyte antigens (HLA) (alleles) and haplotypes. Japanese HTLV-I carriers were characterized by two categories of HLA class I antigens (A24, A26, B7, B61, Cw1, and Cw7) and class II alleles (DRB1 *0101, 0803, 1403, 1501, and 1502 and DQB1 *0303, 0501, and 0601); one category was associated with adult T-cell leukemia (ATL) patients and the other with HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP) patients. The ATL-associated haplotypes had unique DRB1-DQB1 alleles (0901-0303, 1501-0602, 1401-0503), which were correlated with a low immune responsiveness to HTLV-I, while the HAM/TSP haplotypes had different DRB1-DQB1 alleles (0101-0501, 0803-0601, 1502-0601), which were correlated with a high immune responsiveness to HTLV-I. Both ATL- and HAM/TSP-associated haplotypes were found among HTLV-I carriers and the patients from other ethnic groups (Jamaican blacks, Andes natives, South American mestizos, and Mashhadi Jews). HLA haplotypes of HTLV-II carriers were different from those of HTLV-I carriers among South American natives. These results suggested that HTLV-I/II infections and the associated diseases might be determined by immunogenetic factors segregated with HLA alleles and haplotypes.

Biologic, immunocytochemical, and cytogenetic characterization of two new human melanoma cell lines: IIB-MEL-LES and IIB-MEL-IAN.

Two human melanoma cell lines, derived from metastases of two patients with epithelioid malignant amelanotic melanomas, and designated IIB-MEL-LES and IIB-MEL-IAN, have been established. Both cell lines have been in continuous culture over 2 years and were propagated continuously for 85 and 75 serial passages, respectively. Morphologically, IIB-MEL-LES is composed predominantly of spindle shaped cells, whereas IIB-MEL-IAN grows as a monolayer of cuboid and stellate shaped cells with many rounded cells in suspension. Immunocytochemical studies revealed that both cell lines express S-100 protein, vimentin, and GD3 and GD2 gangliosides but are negative for keratin and collagen. Both cell lines express HLA class I and HLA-DR antigens in variable proportions. The MAGE-1 gene is expressed only by the IIB-MEL-IAN cell line, as revealed by PCR analysis. Cytogenetic analysis of both cell lines revealed abnormal karyotypes; the modal chromosome numbers of IIB-MEL-LES and IIB-MEL-IAN were 48 and 81, respectively. IIB-MEL-LES cells presented rearrangements in chromosomes 1, 14 and X, gains in chromosomes 10, 20, and 21 losses in chromosomes 15 and Y. The most frequent markers observed in IIB-MEL-IAN cells were 7q+, 10p+, 2p+, i(6p), 2q+, and 10q-. Clonal gains were observed in chromosomes 12 and 21, whereas losses were seen in chromosomes 1, 2, 3, 4, 6, 7, 11, and 17. Both cell lines were capable of forming colonies in soft agar and developed tumors when transplanted into nude mice, reproducing and maintaining the characteristics of the original tumors. These cell lines and their xenografts appear to provide useful systems for studying the biology, genetics and histogenesis of human malignant melanoma and could be utilized for the development of melanoma vaccines.

MHC expression of African green monkeys of Barbados is limited in heterogeneity.

Major histocompatibility complex expression of activated peripheral blood lymphocytes of captive African green monkeys from Barbados and from Africa were analyzed biochemically; class I molecules by one-dimensional isoelectric focusing and class II DR molecules by one-dimensional nonequilibrium pH gradient electrophoresis. Much less diversity was observed in the major histocompatability molecule expression of the African green monkeys of Barbados than in the African cohort.

Cytomegalovirus infection amplifies class I major histocompatibility complex expression on cultured human endothelial cells.

Cytomegalovirus infection, a common complication in immunosuppressed graft recipients, bears an adverse impact on graft survival. Cytomegalovirus enhances the expression of the monotypic determinants of the class I major histocompatibility complex molecule by the endothelium, possibly rendering the endothelial cells more immunogenic and prone to attack by the allogeneic lymphocytes. In the present study, we focused on the effect of cytomegalovirus on the endothelial cell expression of different class I genes, on the relation between the extent of endothelial cell infection and the class I effect, and on the time course of the class I changes induced by the cytomegalovirus infection. Cytomegalovirus infection of primary cultures of human umbilical vein endothelial cells augmented the expression of the A2, A3, and B7 class I major histocompatibility complex genes when compared with uninfected cells. beta 2 microglobulin upregulation by the infected cells paralleled the changes in specific class I expression; this effect was significant only after 7 days after infection. Double immunocytochemical staining and fluorescence-activated cell sorter analysis revealed that the class I enhancement was uniform throughout the umbilical vein endothelial cell monolayer and not restricted to the cells that expressed cytomegalovirus early or late antigens. Ultraviolet-inactivated supernatants from infected umbilical vein endothelial cell did not increase class I expression on uninfected cells. In conclusion, cytomegalovirus might affect graft survival by amplifying the changes in class I expression beyond the sites of viral replication.

Association of human leukocyte class II antigens with rheumatic fever or rheumatic heart disease in a Brazilian population.

BACKGROUND: The incidence of rheumatic heart disease is great in Brazil. We analyzed the distribution of human leukocyte (HLA) antigens in a Brazilian population sample with rheumatic fever or rheumatic heart disease, with the aim of better understanding the mechanisms involved. METHODS AND RESULTS: HLA class I (A, B, and C) and class II (DR and DQ) antigen distribution was studied in 40 patients with diagnosis of rheumatic fever or rheumatic heart disease and compared with a control group of 617 healthy individuals for class I typing, from which 118 were drawn for class II typing. A strong correlation between rheumatic fever and rheumatic heart disease and HLA-DRw53 (72.9% in the disease group versus 39% in the control group: p = 0.00061, relative risk, 4.2; etiologic fraction, 0.43) was found. We also found an increase in the frequency of HLA-DR7 (57.5% in the disease group versus 26.3% in control group: p = 0.00715; relative risk, 3.8; etiologic fraction, 0.56). HLA class I and HLA-DQ typing did not point to any association with these diseases. CONCLUSIONS: HLA-DR7 and HLA-DRw53 are markers for susceptibility to rheumatic fever and rheumatic heart disease in Brazil. These results could be explained by genetic differences resulting from racial or geographical diversity.

Avaliaçäo da especifidade dos anticorpos linfocitotóxicos em lúpus eritematoso sistêmico: correlaçäo com atividade clínica de doença / Evaluation of lymphocytoxic antibodies specificity in systemic lupus erythematosus: correlation with the clinical activity of the disease

Pacientes portadores de lúpus eritematoso sistêmico (LES), caracterizados em relaçäo ao estadiamento clínico, em atividade e remisäo da doença, foram estudados quanto a presença de anticorpos linfocitotóxicos ciruclantes no soro, através da citoxicidade mediada por complemento (CMC). Soros de 35 pacientes (42 soros) foram testados contra painel de linfócitos periféricos de 31 indivíduos normais com tipagem para antígenos HLA classe I conhecidos (HLA A, B e C), e os experimentos executados em diferentes diluiçöes e temperaturas. As análises demonstraram que 66,66% dos soros apresentaram anticorpos linfocitotóxicos dirigidos contra células de pelo menos um dos doadores normais. A freqüência destes anticorpos mostrou significância estatística nos pacientes em atividade (80,95%) quando comparados aos em remissäo (52,38%). Doentes lúpicos que recebiam diferentes doses de corticosteróides foram separados em grupos, e concluímos que a CMC independe da quantidade de prednisona recebida pelos pacientes. Na maioria dos casos os anticorpos linfocitotóxicos näo estavam dirigidos contra os determinantes anigénicos de histocompatibilidade classe I, pois apenas 3 dos 42 soros reconheceram de forma constante células de doadores, especialmente os de antígenos HLA A1, A2, A3, A11, B5 e B35, permitindo inferir que outros marcadores da superfície linfocitária sejam os maiores pela CMC encontrada nos pacientes com LES. Neste estudo näo observamos variaçöes na identificaçäo dos anticorpos linfocitotóxicos quando executamos as reaçöes nas diferentes temperaturas (4- e 22-C)