B-cell capacity for differentiation changes with age.

BACKGROUND: Age-related immune deficiencies are thought to be responsible for increased susceptibility to infection in older adults, with alterations in lymphocyte populations becoming more prevalent over time. The loss of humoral immunity in ageing was attributed to the diminished numbers of B cells and the reduced ability to generate immunoglobulin. AIMS: To compare the intrinsic B-cell capacity for differentiation into mature plasma cells (PCs), between young and old donors, using in vitro assays, providing either effective T-cell help or activation via TLR engagement. METHODS: B cells were isolated from healthy individuals, in younger (30-38 years) and older (60-64 years) donors. An in vitro model system of B-cell differentiation was used, analysing 5 differentiation markers by flow cytometry, under T-dependent (TD: CD40/BCR stimulation) or T-independent (TI: TLR7/BCR activation) conditions. Antibody secretion was measured by ELISA and gene expression using qPCR. RESULTS: TI and TD differentiation resulted in effective proliferation of B cells followed by their differentiation into PC. B-cell-executed TI differentiation was faster, all differentiation marker and genes being expressed earlier than under TD differentiation (day 6), although generating less viable cells and lower antibody levels (day 13). Age-related differences in B-cell capacity for differentiation were minimal in TD differentiation. In contrast, in TI differentiation age significantly affected proliferation, viability, differentiation, antibody secretion and gene expression, older donors being more efficient. CONCLUSION: Altogether, B-cell differentiation into PC appeared similar between age groups when provided with T-cell help, in contrast to TI differentiation, where multiple age-related changes suggest better capacities in older donors. These new findings may help explain the emergence of autoantibodies in ageing.

Activation-induced cytidine deaminase overexpression in double-hit lymphoma: potential target for novel anticancer therapy.

Activation-induced cytidine deaminase (AID) is one kind of the mutant enzymes, which target regulating the immunoglobulin (Ig) gene in Burkitt's lymphoma to initiate class switch recombination (CSR), resulting in c-Myc chromosomal translocation. However, it is not clear that whether AID induces c-Myc/IgH translocation in double-hit lymphoma (DHL) with c-Myc gene translocation. In this study, the AID in DHL tissues and classical diffuse large b-cell lymphoma (DLBCL) tissues were compared. The results suggested that AID is of important value in predicting DHL, stronger CSR of AID was observed in DHL patients, which exhibited AID overexpression and c-Myc gene translocation of DHL after CSR induction. It is concluded that AID directly induces CSR in DHL and may result in c-Myc gene translocation. Targeting AID may be a good treatment regimen for DHL.

Reconstitution of IgG Subclasses following Immunoglobulin Therapy in Adult Primary Hypogammaglobulinemia.

BACKGROUND: Immunoglobulin (Ig) therapy is highly effective in reducing the frequency and severity of infections. However, a subset of patients does not respond adequately. OBJECTIVE: To determine in adult patients with primary hypogammaglobulinemia (a) if failure to reconstitute IgG subclass(es) is associated with inadequate clinical response, (b) whether reconstitution of IgG subclasses differs between routes of Ig administration, (c) which subclasses contribute to low total IgG, and (d) what are the most commonly impaired Streptococcus pneumoniae serotypes. METHODS: A retrospective review of the records of patients with primary hypogammaglobulinemia followed up at the Immunology Clinic between 2010 and 2018 was conducted. Demographic, clinical, and laboratory data were collected. RESULTS: Seventy-one patients with primary hypogammaglobulinemia were included. All subclasses were reconstituted in 85% of the patients. IgG3 and IgG4 were most commonly not reconstituted. Reconstitution occurred in 85% of the patients on intravenous Ig (IVIG), 81% of the patients on conventional subcutaneous Ig (SCIG), and 100% of the patients on enzyme-facilitated subcutaneous Ig (fSCIG). The annual infection rate was 0.87 with IVIG, 0.88 with conventional SCIG, and 0.6 with fSCIG. IgG subclasses contributing to low total IgG included IgG1 (61%), IgG2 (49%), IgG3 (23%), and IgG4 (28%). In patients with concomitant specific antibody deficiency (n = 47), the most commonly impaired antibody responses were against pneumococcal serotypes 3, 4, 6b, 12f, and 23f. CONCLUSIONS: Failure to reconstitute subclasses does not correlate with an inadequate clinical response to immunoglobulin therapy in primary hypogammaglobulinemia. Full reconstitution of IgG subclasses was observed with fSCIG. A smaller panel of pneumococcal antibody responses may be used to define specific antibody deficiency.

Serotype-Independent Protection Against Invasive Pneumococcal Infections Conferred by Live Vaccine With lgt Deletion.

Streptococcus pneumoniae is the most common respiratory bacterial pathogen among cases of community-acquired infection in young children, older adults, and individuals with underlying medical conditions. Although capsular polysaccharide-based pneumococcal vaccines have contributed to significant decrease in invasive pneumococcal infections, these vaccines have some limitations, including limited serotype coverage, lack of effective mucosal antibody responses, and high costs. In this study, we investigated the safety and immunogenicity of a live, whole-cell pneumococcal vaccine constructed by deleting the gene for prolipoprotein diacylglyceryl transferase (lgt) from the encapsulated pneumococcal strain TIGR4 (TIGR4Δlgt) for protection against heterologous pneumococcal strains. Pneumococcal strain TIGR4 was successfully attenuated by deletion of lgt, resulting in the loss of inflammatory activity and virulence. TIGR4Δlgt colonized the nasopharynx long enough to induce strong mucosal IgA and IgG2b-dominant systemic antibody responses that were cross-reactive to heterologous pneumococcal serotypes. Finally, intranasal immunization with TIGR4Δlgt provided serotype-independent protection against pneumococcal challenge in mice. Taken together, our results suggest that TIGR4Δlgt is an avirulent and attractive broad-spectrum pneumococcal vaccine candidate. More broadly, we assert that modulation of such "master" metabolic genes represents an emerging strategy for developing more effective vaccines against numerous infectious agents.

Autoimmunity and allergy control in adults submitted to complete thymectomy early in infancy.

The contribution of the decline in thymic activity for the emergence of autoimmunity is still debatable. Immune-competent adults submitted to complete thymectomy early in life provide a unique model to address this question. We applied here strict criteria to identify adults lacking thymic activity based on sjTREC levels, to exclude thymic rebound and/or ectopic thymuses. In agreement, they featured severe naïve CD4 T-cell depletion and contraction of T-cell receptor diversity. Notwithstanding this, there was neither increased incidence of autoimmune disease in comparison with age-matched controls nor significant changes in their IgG/IgA/IgM/IgE autoreactivity profiles, as assessed through extensive arrays. We reasoned that the observed relative preservation of the regulatory T-cell compartment, including maintenance of naïve regulatory CD4 T-cells, may contribute to limit the emergence of autoimmunity upon thymectomy. Our findings have implications in other clinical settings with impaired thymic activity, and are particularly relevant to studies of autoimmunity in ageing.

Immunization with Recombinantly Expressed LRP4 Induces Experimental Autoimmune Myasthenia Gravis in C57BL/6 Mice.

BACKGROUND: Myasthenia gravis (MG) is an autoimmune disease of the neuromuscular junction (NMJ), characterized with muscle weakness. While MG develops due to acetylcholine receptor (AChR) antibodies in most patients, antibodies to muscle-specific receptor tyrosine kinase (MuSK) or low-density lipoprotein receptor-related protein 4 (LRP4) may also be identified. Experimental autoimmune myasthenia gravis (EAMG) has been previously induced by both LRP4 immunization and passive transfer of LRP4 antibodies. OBJECTIVE: Our aim was to confirm previous results and to test the pathogenic effects of LRP4 immunization in a commonly used mouse strain C57BL/6 (B6) using a recombinantly expressed human LRP4 protein. METHODS: B6 mice were immunized with human LRP4 in CFA, Torpedo Californica AChR in CFA or only CFA. Clinical and pathogenic aspects of EAMG were compared among groups. RESULTS: LRP4- and AChR-immunized mice showed comparable EAMG clinical severity. LRP4-immunized mice displayed serum antibodies to LRP4 and NMJ IgG and complement factor C3 deposits. IgG2 was the dominant anti-LRP4 isotype. Cultured lymph node cells of LRP4- and AChR-immunized mice gave identical pro-inflammatory cytokine (IL-6, IFN-γ and IL-17) responses to LRP4 and AChR stimulation, respectively. CONCLUSION: Our results confirm the EAMG-inducing action of LRP4 immunization and identify B6 as a LRP4-EAMG-susceptible mouse strain. Demonstration of complement fixing anti-LRP4 antibodies in sera and complement/IgG deposits at the NMJ of LRP4-immunized mice indicates complement activation as a putative pathogenic mechanism. We have thus developed a practical LRP4-induced EAMG model using a non-conformational protein and a widely available mouse strain for future investigation of LRP4-related MG.

Cerebrospinal fluid data compilation and knowledge-based interpretation of bacterial, viral, parasitic, oncological, chronic inflammatory and demyelinating diseases. Diagnostic patterns not to be missed in neurology and psychiatry.

The analysis of intrathecal IgG, IgA and IgM synthesis in cerebrospinal fluid (CSF) and evaluation in combined quotient diagrams provides disease-related patterns. The compilation with complementary parameters (barrier function, i.e., CSF flow rate, cytology, lactate, antibodies) in a cumulative CSF data report allows a knowledge-based interpretation and provides analytical and medical plausibility for the quality assessment in CSF laboratories. The diagnostic relevance is described for neurological and psychiatric diseases, for which CSF analysis can't be replaced by other diagnostic methods without loss of information. Dominance of intrathecal IgM, IgA or three class immune responses give a systematic approach for Facial nerve palsy, Neurotrypanosomiasis, Opportunistic diseases, lymphoma, Neurotuberculosis, Adrenoleucodystrophy or tumor metastases. Particular applications consider the diagnostic power of the polyspecific antibody response (MRZ-antibodies) in multiple sclerosis, a CSF-related systematic view on differential diagnostic of psychiatric diseases and the dynamics of brain- derived compared to blood-derived molecules in CSF for localization of paracytes.

Cerebrospinal fluid data compilation and knowledge-based interpretation of bacterial, viral, parasitic, oncological, chronic inflammatory and demyelinating diseases. Diagnostic patterns not to be missed in neurology and psychiatry / Liquido cefalorraquidiano: compilação dos dados e interpretação avançada de doenças bacterianas, virais, parasitarias, oncológicas, inflamatórias cronicas e desmielinizantes. Padrões diagnósticos que não devem faltar em neurologia e psiquiatria

ABSTRACT The analysis of intrathecal IgG, IgA and IgM synthesis in cerebrospinal fluid (CSF) and evaluation in combined quotient diagrams provides disease-related patterns. The compilation with complementary parameters (barrier function, i.e., CSF flow rate, cytology, lactate, antibodies) in a cumulative CSF data report allows a knowledge-based interpretation and provides analytical and medical plausibility for the quality assessment in CSF laboratories. The diagnostic relevance is described for neurological and psychiatric diseases, for which CSF analysis can’t be replaced by other diagnostic methods without loss of information. Dominance of intrathecal IgM, IgA or three class immune responses give a systematic approach for Facial nerve palsy, Neurotrypanosomiasis, Opportunistic diseases, lymphoma, Neurotuberculosis, Adrenoleucodystrophy or tumor metastases. Particular applications consider the diagnostic power of the polyspecific antibody response (MRZ-antibodies) in multiple sclerosis, a CSF-related systematic view on differential diagnostic of psychiatric diseases and the dynamics of brain- derived compared to blood-derived molecules in CSF for localization of paracytes.

RESUMO A análise da síntese intratecal de IgG, IgA e IgM no liquido cefalorraquidiano (LCR) e a avaliação destas em diagramas com quocientes sugere padrões de diversas doenças. Estes dados, juntamente com outros parâmetros como a função de barreira, o fluxo liquórico, a citologia, o lactato e a pesquisa de anticorpos, integrados em uma ficha de paciente, permite uma interpretação baseada em conhecimento e permite também uma aferição da qualidade em laboratórios de LCR. A relevância diagnóstica é descrita para doenças neurológicas e psiquiátricas pois a análise do LCR não pode ser substituída por outros metódos diagnósticos sem perda de informação para o diagnóstico do paciente. O aumento da síntese intratecal de IgM, IgA ou das 3 classes de imunoglobulinas sugerem um diagnóstico sistemático de paralisia facial periférica, neurotripanosomiase, doenças oportunísticas, linfoma, neurotuberculose, adrenoleucodistrofia ou metástases de tumores cerebrais. A resposta poliespecífica de anticorpos contra sarampo, rubéola e varicela zoster (MRZ reação) é sugestiva de esclerose múltipla. Uma visão sistemática considera o diagnóstico diferencial de doenças psiquiátricas e doenças chrônicas. A dinâmica de moléculas derivadas do cérebro comparadas com aqueles derivadas do sangue é importante para a localização de parasitos em doenças parasitárias do sistema nervoso.

Discovery and bio-optimization of human antibody therapeutics using the XenoMouse® transgenic mouse platform.

Since the late 1990s, the use of transgenic animal platforms has transformed the discovery of fully human therapeutic monoclonal antibodies. The first approved therapy derived from a transgenic platform--the epidermal growth factor receptor antagonist panitumumab to treat advanced colorectal cancer--was developed using XenoMouse(®) technology. Since its approval in 2006, the science of discovering and developing therapeutic monoclonal antibodies derived from the XenoMouse(®) platform has advanced considerably. The emerging array of antibody therapeutics developed using transgenic technologies is expected to include antibodies and antibody fragments with novel mechanisms of action and extreme potencies. In addition to these impressive functional properties, these antibodies will be designed to have superior biophysical properties that enable highly efficient large-scale manufacturing methods. Achieving these new heights in antibody drug discovery will ultimately bring better medicines to patients. Here, we review best practices for the discovery and bio-optimization of monoclonal antibodies that fit functional design goals and meet high manufacturing standards.

Ontogeny, tissue distribution and expression analysis of IgZ in rohu, Labeo rohita in response to various stimuli.

This study reports presence of IgZ transcripts, its ontogeny, tissue distribution and expression following various stimulations/infections in rohu. The derived rohu IgZ sequence clustered together with IgZ of Ctenopharyngodon idella and Cyprinus carpio in phylogenetic analysis. IgZ expression was detected at early developmental stages with higher expression at 1 day post-fertilization, and higher in anterior kidney and lower in skin tissues of juveniles. An inductive expression of IgZ was observed during both Edwardsiella tarda and Dactylogyrus catlaius infections in skin and/or gill tissues. In ConA treated HKLs, the response was prominent at 72 h post-stimulation where as in ConA-PMA treatment, it was higher during early time points. Increased expression of IgZ was found between 24 and 96 hps with formalin-killed Aeromonas hydrophila where as in poly I:C treated HKLs, the level increased at 96 hps. It seems to be the first report describing the functional existence of IgZ in rohu carp.

Efficient generation of human IgA monoclonal antibodies.

Immunoglobulin A (IgA) is the most abundant antibody isotype produced in humans. IgA antibodies primarily ensure immune protection of mucosal surfaces against invading pathogens, but also circulate and are present in large quantities in blood. IgAs are heterogeneous at a molecular level, with two IgA subtypes and the capacity to form multimers by interacting with the joining (J) chain. Here, we have developed an efficient strategy to rapidly generate human IgA1 and IgA2 monoclonal antibodies in their monomeric and dimeric forms. Recombinant monomeric and dimeric IgA1/IgA2 counterparts of a prototypical IgG1 monoclonal antibody, 10-1074, targeting the HIV-1 envelope protein, were produced in large amounts after expression cloning and transient transfection of 293-F cells. 10-1074 IgAs were FPLC-purified using a novel affinity-based resin engrafted with anti-IgA chimeric Fabs, followed by a monomers/multimers separation using size exclusion-based FPLC. ELISA binding experiments confirmed that the artificial IgA class switching of 10-1074 did not alter its antigen recognition. In summary, our technical approach allows the very efficient production of various forms of purified recombinant human IgA molecules, which are precious tools in dissecting IgA B-cell responses in physiological and pathophysiological conditions, and studying the biology, function and therapeutic potential of IgAs.

The role of metalloproteinase ADAM17 in regulating ICOS ligand-mediated humoral immune responses.

Immune cells regulate cell surface receptor expression during their maturation, activation, and motility. Although many of these receptors are regulated largely at the level of expression, protease-mediated ectodomain shedding represents an alternative means of refashioning the surface of immune cells. Shedding is largely attributed to a family of a disintegrin and metalloprotease domain (ADAM) metalloproteases, including ADAM17. Although ADAM17 is well known to contribute to the innate immune response, mainly by releasing TNF-α, much less is known about whether/how this metalloprotease regulates adaptive immunity. To determine whether ADAM17 contributes to regulating adaptive immune responses, we took advantage of ADAM17 hypomorphic (ADAM17(ex/ex)) mice, in which ADAM17 expression is reduced by 90-95% compared with wild-type littermates. In this study, we show that that ADAM17 deficiency results in spleen and lymph node enlargement, as well as increased levels of Ag-specific class-switched Ig production following immunization with OVA together with anti-CD40 mAbs and polyinosinic-polycytidylic acid. Moreover, we demonstrate that the costimulatory ligand ICOS ligand (ICOSL) is selectively downregulated on the surface of B cells in an ADAM17-specific manner, although it is not proteolitically processed by recombinant ADAM17 in vitro. Finally, we show that higher cell surface levels of ICOSL in ADAM17(ex/ex) mice may contribute to the development of excessive Ab responses. Therefore, our data suggest a functional link between ADAM17 and ICOSL in controlling adaptive immune responses.

Follicular dendritic cell secreted protein FDC-SP controls IgA production.

Follicular dendritic cell secreted protein (FDC-SP) is a secreted peptide predominantly expressed in mucosal tissues. We previously reported that FDC-SP transgenic mice have altered B-cell responses to systemic immunization; however, the role of FDC-SP in mucosal immunity is unknown. Here, we report that FDC-SP functions in regulating immunoglobulin A production. FDC-SP transgenic mice show decreased IgA levels in serum, saliva, and bronchoalveolar lavage fluid. Reciprocally, FDC-SP-deficient mice show significantly increased IgA levels in serum and intestinal lavage, associated with accumulation of IgA+ cells in blood, bone marrow, Peyer's patches, and lymph nodes. FDC-SP-deficient mice generated higher titers of antigen-specific IgA but normal IgG1 responses upon immunization. Purified FDC-SP transgenic B cells generated decreased IgA responses to transforming growth factor ß (TGFß)+interleukin 5 (IL5) stimulation. Consistent with a direct effect of FDC-SP on B cells, recombinant FDC-SP suppressed B-cell IgA production in vitro. Six- to 14-month-old FDC-SP-deficient mice show IgA deposition in kidney glomeruli, which was associated with proteinuria and pathology consistent with mild IgA nephropathy (IgAN). Our results demonstrate a novel biological activity of FDC-SP in controlling B-cell IgA production and identify FDC-SP-deficient mice as a novel mouse model of IgAN.

CCL19 and CCL28 augment mucosal and systemic immune responses to HIV-1 gp140 by mobilizing responsive immunocytes into secondary lymph nodes and mucosal tissue.

Induction of broad and potent neutralizing Abs at the mucosal portals of entry remains a primary goal for most vaccines against mucosally acquired viral infections. Selection of appropriate adjuvants capable of promoting both systemic and mucosal responses will be crucial for the development of effective immunization strategies. In this study, we investigated whether plasmid codelivery of cytokines APRIL, CCL19, or CCL28 can enhance Ag-induced immune responses to HIV-1 gp140. Our results demonstrated that pCCL19 and pCCL28, but not pAPRIL, significantly enhanced Ag-specific systemic and mucosal Ab responses. gp140-specific Abs in serum enhanced by pCCL19 or pCCL28 were broadly distributed across all four IgG subclasses, of which IgG1 was predominant. The enhanced systemic and mucosal Abs showed increased neutralizing activity against both homologous and heterologous HIV-1, and potency correlated with gp140-specific serum IgG and vaginal IgA levels. Measurement of gp140-specific cytokines produced by splenocytes demonstrated that pCCL19 and pCCL28 augmented balanced Th1/Th2 responses. pCCL19 and pCCL28 also increased IgA(+) cells in colorectal mucosal tissue. pCCL19 codelivery resulted in an increase of CCR7(+) CD11c(+) cells in mesenteric lymph nodes and both CCR7(+) CD11c(+) cells and CCR7(+) CD3e(+) cells in spleen, whereas pCCL28 codelivery resulted in an augment of CCR10(+) CD19(+) cells in both spleen and mesenteric lymph nodes. Together, our data indicate that pCCL19 and pCCL28 can enhance HIV-1 envelope-specific systemic and mucosal Ab responses, as well as T cell responses. Such enhancements appear to be associated with mobilization of responsive immunocytes into secondary lymphoid organs and mucosal tissues through interactions with corresponding receptors.

Clinical significance of the fluctuation of primary biliary cirrhosis-related autoantibodies during the course of the disease.

Primary biliary cirrhosis (PBC) is a chronic cholestatic disease characterized by the presence of antimitochondrial antibodies (AMA). PBC-specific antinuclear antibodies (ANA) have been characterized and associated with disease progression and outcome. We evaluated the clinical significance of the presence and serial changes in titers of AMA, PBC-specific ANA (anti-gp210, anti-sp100) and anti-chromatin antibodies. Over a median (IQR) period of 35 (36) months, 512 specimens were collected from 110 patients. Autoantibodies were detected by commercial ELISAs (INOVA Diagnostics). Biochemical, clinical, and histological status were included at initial presentation and during follow-up visits. The Mayo risk score was calculated as a prognostic index at each time point. Liver biopsy findings were classified according to Ludwig's classification and biochemical response to ursodeoxycholic acid was evaluated according to Pares. At baseline, AMA IgG and IgA, anti-gp210 IgG, anti-sp100 IgG and anti-chromatin IgG were detected in 92/110 (83.6%), 57/110 (51.8%), 5/110 (4.5%), 14/110 (12.7%), and 0/110 (0%) patients, respectively. Positivity for all autoantibodies apart from anti-chromatin, at baseline visit (n = 110 patients), in all tested sera (n = 512) as well as increased autoantibodies titers during follow-up were associated with biochemically and/or histologically advanced disease. A decrease of anti-sp100 titers but not of anti-gp210 titers during follow-up was associated with improvement of Mayo risk score (p = 0.025) and response to ursodeoxycholic acid (p = 0.016). These results suggest that detection of AMA and PBC-specific ANA was correlated with disease severity. Serial changes of anti-sp100 titers and not of anti-gp210 titers might prove useful for monitoring the disease course and treatment outcome.

Memory B cells in mouse models.

One of the principles behind vaccination, as shown by Edward Jenner in 1796, and host protection is immunological memory, and one of the cells central to this is the antigen-experienced memory B cell that responds rapidly upon re-exposure to the initiating antigen. Classically, memory B cells have been defined as progenies of germinal centre (GC) B cells expressing isotype-switched and substantially mutated B cell receptors (BCRs), that is, membrane-bound antibodies. However, it has become apparent over the last decade that this is not the only pathway to B cell memory. Here, we will discuss memory B cells in mice, as defined by (1) cell surface markers; (2) multiple layers; (3) formation in a T cell-dependent and either GC-dependent or GC-independent manner; (4) formation in a T cell-independent fashion. Lastly, we will touch upon memory B cells in; (5) mouse models of autoimmune diseases.

Production of seven monoclonal equine immunoglobulins isotyped by multiplex analysis.

Horses have 11 immunoglobulin isotypes: IgM, IgD, IgA, IgE, and seven IgG subclasses designated as IgG1-IgG7, each of which are distinguished by separate genes encoding the constant heavy chain regions. Immunoglobulin (Ig) isotypes have different functions during the immune response and pathogen-specific isotypes can be used as indicators for immunity and protection from disease. In addition to existing monoclonal antibodies to various equine Igs, quantification of the individual isotypes requires pure isotype standards. In this report, we describe a fusion between X63-Ag8.653 mouse myeloma cells and horse PBMC to create equine-murine heterohybridomas. Initial screening for Ig production was performed by ELISA. Further testing was performed by a new 5-plex fluorescent bead-based assay able to simultaneously detect equine IgM, IgG1, IgG4/7, IgG5, and IgG6. Production of IgG3 and IgE was tested by separate bead assays. Seven stable heterohybridoma clones producing monoclonal equine IgM, IgG1, IgG3, IgG4/7, IgG5, IgG6 and IgE were created. Purified Ig isotypes were then tested by SDS-PAGE. The pure, monoclonal equine Ig isotypes and the new equine Ig multiplex testing developed here are valuable tools to quantify antibody responses and to accurately determine individual isotypes concentrations in horses.

Antibody response to Mycobacterium tuberculosis p27-PPE36 antigen in sera of pulmonary tuberculosis patients.

We have expressed, characterized and studied the immune response of mice against the Mycobacterium tuberculosis PPE36 protein. This protein encoded by the gene Rv2108 is a 27-kDa cell-wall associated protein. Here, we compare the antibody isotypes distribution of p27-PPE36 in sera of pulmonary tuberculosis patients and in sera from healthy control subjects by enzyme-linked immunosorbent assay (ELISA). We detected in the sera of affected individuals a significant increase of IgA antibody response, a no significant augmentation of IgM response, a complete lack of IgG2, 3, and 4 responses and a weak IgG1 response in a few subjects.

Early adaptive immune responses in the respiratory tract of foot-and-mouth disease virus-infected cattle.

Foot-and-mouth disease (FMD) is a highly contagious viral disease which affects both domestic and wild biungulate species. This acute disease, caused by the FMD virus (FMDV), usually includes an active replication phase in the respiratory tract for up to 72 h postinfection, followed by hematogenous dissemination and vesicular lesions at oral and foot epithelia. The role of the early local adaptive immunity of the host in the outcome of the infection is not well understood. Here we report the kinetics of appearance of FMDV-specific antibody-secreting cells (ASC) in lymphoid organs along the respiratory tract and the spleen in cattle infected by aerosol exposure. While no responses were observed for up to 3 days postinfection (dpi), all animals developed FMDV-ASC in all the lymphoid organs studied at 4 dpi. Tracheobronchial lymph nodes were the most reactive organs at this time, and IgM was the predominant isotype, followed by IgG1. Numbers of FMDV-ASC were further augmented at 5 and 6 dpi, with an increasing prevalence in upper respiratory organs. Systemic antibody responses were slightly delayed compared with the local reaction. Also, IgM was the dominant isotype in serum at 5 dpi, coinciding with a sharp decrease of viral RNA detection in peripheral blood. These results indicate that following aerogenous administration, cattle develop a rapid and vigorous genuine local antibody response throughout the respiratory tract. Time course and isotype profiles indicate the presence of an efficient T cell-independent antibody response which drives the IgM-mediated virus clearance in cattle infected by FMDV aerosol exposure.

µ-chain-deficient mice possess B-1 cells and produce IgG and IgE, but not IgA, following systemic sensitization and inhalational challenge in a fungal asthma model.

Allergic bronchopulmonary aspergillosis is often difficult to treat and results in morbidity associated with chronic airway changes. This study assessed the requirement for B cells and their products in the allergic pulmonary phenotype in a murine model of fungal allergic asthma that mimics allergic bronchopulmonary aspergillosis. C57BL/6 and µMT mice (assumed to lack peripheral B cells) were sensitized with Aspergillus fumigatus extract and challenged with two inhalation exposures of live conidia to induce airway disease. Airway hyperresponsiveness after methacholine challenge, peribronchovascular inflammation, goblet cell metaplasia, and fibrotic remodeling of the airways was similar between µMT mice and their wild-type counterparts (C57BL/6). Surprisingly, even in the absence of the µ-chain, these µMT mice produced IgE and IgG Abs, although the Abs induced did not have specificity for A. fumigatus Ags. In contrast, IgA was not detected in either the lavage fluid or serum of µMT mice that had been exposed to A. fumigatus. Our findings also reveal the existence of CD19(+)CD9(+)IgD(+) B-1 cells in the lungs of the µMT animals. These data show the µMT mice to have a developmental pathway independent of the canonical µ-chain route that allows for their survival upon antigenic challenge with A. fumigatus conidia, although this pathway does not seem to allow for the normal development of Ag-specific repertoires. Additionally, this study shows that IgA is not required for either clearance or containment of A. fumigatus in the murine lung, as fungal outgrowth was not observed in the µMT animals after multiple inhalation exposures to live conidia.