Specificities of IgM and IgG anti-histone H1 autoantibodies in autoimmune mice.

Autoantibodies to histone H1 represent the most common specificity among anti-histone autoantibodies in systemic autoimmune diseases. Here we analyse anti-H1 autoantibodies in mice from the following autoimmune strains: MRL/Mp-lpr/lpr, NZB and NZB x NZW/F1. Autoantibodies of the IgM isotype bind predominantly to epitopes located in the COOH-terminal domain of the H1 molecule, whereas IgG autoantibodies in the MRL/Mp-lpr/lpr and NZB strains also recognize epitopes requiring the integrity of both the COOH-terminal and the central globular domains of H1. In both of these strains, the titre of these IgG anti-H1 antibodies rises during the course of the disease. The importance of three-dimensional structure of histone H1 was attested by a significant decrease in IgG binding after cleavage of the H1 molecule within the folded globular domain. The binding of these sera to H1 variants from various species was also investigated and a strong binding of MRL/Mp-lpr/lpr sera to certain phylogenetically distant histone H1 variant molecules (sea-urchin sperm H1 and chicken erythrocyte H5) was observed. This cross-reacting binding can be explained by the presence in MRL/Mp-lpr/lpr sera of autoantibodies to H1(0), a variant found in non-dividing cells and exhibiting sequence homologies to the above mentioned variants. The significance and the possible implications of these data for the pathogenesis of autoimmunity are discussed.     

Antibodies from patients with systemic lupus erythematosus and drug-induced lupus bind determinants on histone 5 (H5).

The antigenic domains of histone 5 (H5), a highly conserved variant of histone 1 (H1), were studied in relation to their reactivity with autoantibodies found in the sera of patients with systemic lupus erythematosus (SLE) and drug-induced lupus (DIL). While some H5 antibodies cross-react with H1, adsorption and immunoblotting studies have identified H5-specific antibodies as well. After proteolytic cleavage of H5 peptides, the reactivity of sera from these patients was tested by Western immunoblotting. All SLE (9/9) and DIL (7/7) sera bound an antigenic determinant in the carboxyl (C) terminus of H5 while none of the sera bound to the amino (N) terminus or the central hydrophobic domain. Although the reactivity of DIL sera with the purified H5 peptides was weaker than that of SLE sera, the antigenic domains bound by both groups of sera were the same. These observations demonstrate that the H5 domains reacting with DIL sera are restricted to the carboxyl terminus and are therefore no less restricted than those reacting with SLE sera. Further, the potential epitopes in the carboxyl terminus of H5 do not have a high degree of sequence identity with known mammalian peptides.     

Epitope recognition in histone H1 by SLE autoantibodies in the presence of a DNA-ligand.

To investigate the specificity of anti H1 antibodies peptides from the N- and C-domain of H1 and the synthetic oligonucleotide (AT)6 were complexed. Circular dichroism (CD) spectroscopy indicated that the free peptides H1(1-16), H1(204-218) and C(121-210) in low salt buffer assume a random structure but become helical when bound to the oligonucleotide. The structured and unstructured H1 fragments were then analyzed by enzyme linked immunosorbent assay (ELISA) with anti-H1 antibodies in sera from patients with systemic lupus erythematosis (SLE) and with the monoclonal anti-H1 antibody MRA-12 derived from MLR lpr/lpr autoimmune mice. Binding of these antibodies to H1(204-218) and C was inhibited to a level of 50% when these H1 peptides were complexed with (AT)6. When the same antibody was tested with H1 fragment GC(34-210), attachment to oligonucleotide (AT)6 did not influence antibody binding. Competition studies with liquid phase GC and C antigen against solid phase GC and C indicated that liquid phase GC was more efficient in displacing antibody binding reactivity than liquid phase C. The displacement effect of both liquid phase antigens was greatest against solid phase C. We conclude that anti-H1 autoantibodies are directed against an epitope located near the junction of the G- and C-domain which is exposed and not masked when H1 is bound to DNA.     

Relationship between autoepitope and DNA-binding site on a histone H1 molecule.

Autoepitope and DNA-binding domain on a histone H1 molecule were compared using truncated histone H1 peptides as antigens. At least two epitopes (epitope A, N-terminal side; epitope B, C-terminal side) were found both of which were composed of approximately 20 amino acids. IgM from all 17 anti-histone H1-positive SLE sera reacted with epitope A. IgG from 12 sera reacted with epitope A and IgG from 4 sera reacted with epitope B. In one case, no IgG anti-histone H1 reactivities were found while IgM from the same patient reacted with epitope A. Epitope A had the ability to bind DNA. The reactivities against histone H1 of affinity-purified antiepitope A autoantibodies were inhibited by DNA. These data suggest that some anti-histone H1 antibodies are directed against a histone H1 DNA-binding site, raising the possibility that an idiotype/anti-idiotype network, at least in part, is involved in the generation of anti-histone H1 autoantibodies.     

Factor H autoantibodies in membranoproliferative glomerulonephritis

Factor H autoantibodies are found in ~10% of aHUS patients. Most are associated with complete deficiency of factor H related proteins 1/3 and bind to the C terminal recognition domain. MPGN, like aHUS, is characterised by complement activation. In this study we, therefore, examined the hypothesis that factor H autoantibodies are associated with MPGN. We screened sera from 16 MPGN patients and 100 normal controls using ELISA and detected strongly positive IgG factor H autoantibodies in 2 patients. One patient had type II (DDD) MPGN (male aged 24 yrs) with C3NeF and the other type I (female aged 26 yrs) with no detectable C3NeF. We identified the binding site of the autoantibodies using small SCR domain fragments in the ELISA and showed that the autoantibodies in both patients bound predominately to the N terminal complement regulatory domain of factor H. We measured CFHR 1/3 copy number using MLPA and showed that both patients had 2 copies of CFHR1 and 3. Finally, we examined the functionality of detected factor H autoantibodies using purified patient IgG and observed increased haemolysis when purified IgG from both patients was added to normal human sera prior to incubation with rabbit red blood cells. Thus, in a cohort of MPGN patients we have found a high titre of functionally significant factor H autoantibodies in two patients with MPGN. Antibody depleting therapy may have a role in such patients and we suggest that screening for factor H autoantibodies should be undertaken in all patients with MPGN.     

Factor H autoantibodies in membranoproliferative glomerulonephritis

Factor H autoantibodies are found in ∼10% of aHUS patients. Most are associated with complete deficiency of factor H related proteins 1/3 and bind to the C terminal recognition domain. MPGN, like aHUS, is characterised by complement activation. In this study we, therefore, examined the hypothesis that factor H autoantibodies are associated with MPGN. We screened sera from 16 MPGN patients and 100 normal controls using ELISA and detected strongly positive IgG factor H autoantibodies in 2 patients. One patient had type II (DDD) MPGN (male aged 24 yrs) with C3NeF and the other type I (female aged 26 yrs) with no detectable C3NeF. We identified the binding site of the autoantibodies using small SCR domain fragments in the ELISA and showed that the autoantibodies in both patients bound predominately to the N terminal complement regulatory domain of factor H. We measured CFHR 1/3 copy number using MLPA and showed that both patients had 2 copies of CFHR1 and 3. Finally, we examined the functionality of detected factor H autoantibodies using purified patient IgG and observed increased haemolysis when purified IgG from both patients was added to normal human sera prior to incubation with rabbit red blood cells. Thus, in a cohort of MPGN patients we have found a high titre of functionally significant factor H autoantibodies in two patients with MPGN. Antibody depleting therapy may have a role in such patients and we suggest that screening for factor H autoantibodies should be undertaken in all patients with MPGN.     

Anti-LC1 autoantibodies in patients with chronic hepatitis C virus infection

Various autoantibodies have been reported in patients chronically infected by hepatitis C virus. 2% to 10% of theses patients have anti-liver-kidney microsome type 1 (anti-LKM1) autoantibodies. In type 2 autoimmune hepatitis, anti-LKM1 autoantibodies are frequently associated with anti-liver-cytosol type 1 (anti-LC1) autoantibodies. AIMS: To determine the prevalence of anti-LC1 autoantibodies in a hepatitis C-positive population and characterize their reactivity. METHODS: 146 patients suffering from liver diseases, of which 99 were chronically infected by hepatitis C virus, were tested by Western blotting and immunoprecipitation to detect and characterize anti-LC1 autoantibodies. RESULTS: 12% of this hepatitis C population had anti-LC1 autoantibodies. LC1 positivity by Western blotting was 30% of LC1+ sera. Epitopes were found throughout the protein but linear epitopes were situated in the 395-541 amino acid region of formiminotransferase cyclodeaminase. Three putative conformational epitopes were identified by phage display. CONCLUSIONS: Anti-LC1 autoantibodies are as prevalent as anti-LKM1 autoantibodies in patients infected with hepatitis C virus and their production is not dependent of anti-LKM1 autoantibodies formation. Autoantibody reactivity against the anti-LC1 antigen is different in hepatitis C than in type 2 autoimmune hepatitis. Anti-LC1 autoantibodies can now be regarded as a serological marker of autoimmunity in chronic hepatitis C infection.     

Specificity of autoantibodies to histone H1 in SLE: relationship to DNA-binding domains.

Autoantibodies in the sera of patients with systemic lupus erythematosus were examined with respect to their specificity for proteolytic fragments of histone H1 that retain, or do not retain, DNA-binding domains. 16 of 31 sera contained IgG and IgM antibodies to histone H1. IgM antibodies to H1 in 8 sera (50%) were directed at 18 kD and 20 kD alpha-chymotrypic H1 fragments that bore binding sites for DNA, as identified by staining immunoblots containing the fragments with ssDNA plus 6/0, a mouse monoclonal antibody against ssDNA, IgM with this type of histone H1 specificity did not react with comparably-sized V8 protease fragments of H1. IgM antibodies to H1 in the other patients were directed against entirely different epitopes which were preserved in V8 protease digests of H1. In serial studies of three patients during different phase of their SLE, the level of antibodies against the 18 kD and 20 kD histone H1 fragments varied in parallel with the level of anti-ssDNA antibodies in one and varied inversely in the other two. The data suggest that a significant proportion of autoantibodies to histone H1 are directed at a limited number of epitopes localized to H1 fragments containing DNA-binding sites.     

A new autoreactive monoclonal antibody specific for the Thy-1 antigen

The present study describes the development of a new IgM monoclonal autoantibody reactive with the Thy-1 antigen. The C16-31 monoclonal antibody (mAb) was considered as autoreactive because it reacted with thymus cells of both the C3H and BALB/c strains, which were involved in the development of the antibody. The antibody was reactive with thymus cells in both immunofluorescent and cytotoxic tests. It also showed a weak immunofluorescent reactivity with peripheral T-lymphocytes. The identification of the specificity detected by the C16-31 mAb as the Thy-1 antigen was based on the following criteria: C16-31 mAB displayed a preferential reactivity with Thy-1.2 bearing thymus cells, rather than with Thy-1.1 bearing thymus cells. The tissue distribution of the antigen detected by the C16-31 antibody by direct tests and by direct tests and by adsorption experiments was in accordance with that characteristic for Thy-1. It was high on brain tissue and on thymus cells, and considerably lower on peripheral T-lymphocytes. Coating of thymocytes with C16-31 antibody blocked their reactivity with other monoclonal Thy-1 antibodies. Conversely, coating of thymus cells with rabbit anti-brain serum (RABR) inhibited the binding of C16-31. The C16-31 mAb differed from the Thy-1 autoantibodies described previously in its relatively strong reactivity with brain tissue and its considerably weaker reactivity with peripheral T-lymphocytes. Moreover, C16-31 mAb showed a preferential allospecificity for Thy-1.2, only in its reactivity with thymocytes. In contrast, it reacted equally well with brain tissue from either Thy-1.2 or Thy-1.1 mice.     

Extent of antigenic cross-reactivity among highly pathogenic H5N1 influenza viruses

Highly pathogenic H5N1 avian influenza viruses emerged in 1996 and have since evolved so extensively that a single strain can no longer be used as a prepandemic vaccine or diagnostic reagent. We therefore sought to identify the H5N1 strains that may best serve as cross-reactive diagnostic reagents. We compared the cross-reactivity of 27 viruses of clades 0, 1, 2.1, 2.2, 2.3, and 4 and of four computationally designed ancestral H5N1 strains by hemagglutination inhibition (HI) and microneutralization (MN) assays. Antigenic cartography was used to analyze the large quantity of resulting data. Cartographs of HI titers with chicken red blood cells were similar to those of MN titers, but HI with horse red blood cells decreased antigenic distances among the H5N1 strains studied. Thus, HI with horse red blood cells seems to be the assay of choice for H5N1 diagnostics. Whereas clade 2.2 antigens were able to detect antibodies raised to most of the tested H5N1 viruses (and clade 2.2-specific antisera detected most of the H5N1 antigens), ancestral strain A exhibited the widest reactivity pattern and hence was the best candidate diagnostic reagent for broad detection of H5N1 strains.     

Antibodies in procainamide-induced and systemic lupus erythematosus bind the C-terminus of histone 1 (H1)

The sera of patients with systemic lupus erythematosus (SLE) and drug-induced lupus (DIL) were used to study the antigenic regions of histone 1 (H1) that bind antibodies in these sera. ELISA and immunoblotting techniques using enzymatically and chemically derived peptides of H1 showed that the major antigenic domain is in the carboxyl (C) terminus. None of the 24 SLE or 11 DIL sera bound to the central hydrophobic polypeptide by ELISA. The reactivity of DIL sera with the purified H1 peptides was similar to that observed with SLE sera. This observation suggests a common immune pathway for DIL and SLE.     

Immune reactivity to GAD25 in type 1 diabetes mellitus

While both isoforms of glutamic acid decarboxylase (GAD) function as important autoantigens in autoimmune diabetes mellitus-GAD65 in humans and GAD67 in the NOD mouse-GAD67 is not synthesized in human pancreatic islets and is thought not to be an autoantigen in human diabetes. We have recently shown, however, that human islets contain a GAD67 splice variant: GAD25. Given the evidence that GAD67 could be a key diabetogenic autoantigen in the NOD mouse and the high prevalence of GAD65 autoantibodies in human type 1 diabetes, it became important to ask whether there is also immune reactivity to GAD25 in type 1 diabetes-possibly implicating it in the pathogenesis of the disease-and whether GAD25 reactivity could, like GAD65 reactivity, function as a clinically useful marker for the disease. We also hypothesized that the presence of autoantibodies to the smaller splice variant could be a cause of the up to 30% prevalence of GAD67 autoreactivity associated with type 1 diabetes. We therefore analyzed GAD25 reactivity in 105 newly-diagnosed children with type 1 diabetes and 74 control subjects. While 14 (13%) of the diabetic subjects were positive for GAD67 autoantibodies, only 3 (3%) were positive for GAD25 reactivity, none of which were GAD67 antibody-positive. Analysis of reactivity to a GAD67 chimera was consistent with GAD67 binding activity being due to cross-reactive GAD65 antibodies. Immunostaining confirmed the presence of GAD25 in human islets, revealing GAD25-positive cells to be sparse. Our results indicate that autoreactivity to GAD25 is rare in newly diagnosed type 1 diabetes and does not underlie GAD67 reactivity.     

H5N1流感病毒M1蛋白免疫制备的单克隆抗体的研究

目的 制备抗人流感病毒H5N1株M1蛋白的单克隆抗体,为流感的快速诊断和研究提供新的工具.方法 应用在大肠埃希菌中表达的人H5N1亚型禽流感病毒(A/Anhui/1/2005)株M1蛋白,以纯化的表达产物免疫BALB/c小鼠,取脾细胞与sp2/0细胞系作细胞融合后,间接ELISA法筛选阳性的杂交瘤细胞,并应用间接免疫荧光法对抗体的特异性进行鉴定.结果 获得3株能稳定分泌抗禽流感病毒M1抗原的McAb杂交瘤细胞株,交叉反应试验及间接免疫荧光检测表明,三株McAb具有型特异性.结论 用H5N1禽流感病毒M1蛋白免疫制备的单克隆抗体,具有一定的交叉反应性,可用于多种亚型甲型流感病毒的检测.     

Histone H1(0) mapping using monoclonal antibodies

Monoclonal antibodies (mAb) to ox liver histone H1 degree were produced and characterized. Two sets of mice were immunized either with pure H1(0) or with an H1(0)-yeast tRNA complex. Eleven hybridomas of various clonal origin were selected. Typing of the antibodies indicated that all but three IgM belonged to the IgG1 class and contained kappa light chains. Immunoblotting experiments using peptides derived from H1(0) or H5 treated by various proteolytic agents (trypsin, N-bromosuccinimide, cyanogen bromide, acetic acid), revealed that nine of the mAb reacted with the globular part of H1(0). More advanced characterization of the antigenic determinants allowed us to determine distinct regions within this globular part which are involved in the antigenic recognition. The peptopes could be subdivided into two groups. Three mAb bound to residues 24-27 and were specific for H1(0). Six mAb bound to residues 27-30 and were specific for H1(0) except one of them which strongly cross-reacted with H5 and GH5. Two mAb reacted with the entire histone H1(0) but failed to react with any of the peptides, suggesting that the corresponding epitope is a conformational antigenic determinant. In order to confirm the localization of the two distinct regions which are involved in the antigenic recognition, a synthetic decapeptide corresponding to the beginning of human H1(0) globular part (from residue 19 to residue 28) was synthesized. Inhibition experiments of the reaction between H1(0) and the various IgG1 mAb by increasing amounts of peptide-bovine serum albumin conjugates were then performed.     

Serological study of the 2009 pandemic due to influenza A H1N1 in the metropolitan French population

We looked for evidence of antibodies to the 2009 influenza A/H1N1 pandemic virus in panels of sera from individuals living in metropolitan France, obtained either before, during or after the epidemic, using standard haemagglutination inhibition and microneutralization tests. The difference between seroprevalence values measured in post- and pre-epidemic panels was used as an estimate of seroconversion rate in different age groups (23.4% (0–24 years, age-group 0); 16.5% (25–34); 7.9% (35–44); 7.2% (45–54); 1.6% (55–64); and 3.1% (<65)), confirming that the distribution of cases in different age groups was similar to that of the seasonal H1N1 virus. During the pre-pandemic period low-titre cross-reactive antibodies were present in a large proportion of the population (presumably acquired against seasonal H1N1) whereas cross-reactive antibodies were detected in individuals over the age of 65 years with significantly higher prevalence and serological titres (presumably acquired previously against Spanish flu-related H1N1 strains). Clinical data and analysis of post-pandemic seroprevalence showed that few of these latter patients were infected by the influenza virus during the epidemic. In contrast, the majority of both clinical cases and seroconversions were recorded in the 0–24 age group and a global inverse relationship between prevalence of antibodies to pH1N1 in the pre-pandemic period and rate of seroconversion was observed amongst age groups. Our results emphasize the complex relationships involved in antigenic reactivity to pandemic and seasonal H1N1 viral antigens; hence the difficulty in distinguishing between low-titre specific and cross-reactive antibodies, establishing precise seroprevalence numbers and fully understanding the relationship between previous immunity to seasonal viruses and protection against the novel variant.     

H1N1 viral proteome peptide microarray predicts individuals at risk for H1N1 infection and segregates infection versus Pandemrix® vaccination

A high content peptide microarray containing the entire influenza A virus [A/California/08/2009(H1N1)] proteome and haemagglutinin proteins from 12 other influenza A subtypes, including the haemagglutinin from the [A/South Carolina/1/1918(H1N1)] strain, was used to gauge serum IgG epitope signatures before and after Pandemrix^® vaccination or H1N1 infection in a Swedish cohort during the pandemic influenza season 2009. A very narrow pattern of pandemic flu‐specific IgG epitope recognition was observed in the serum from individuals who later contracted H1N1 infection. Moreover, the pandemic influenza infection generated IgG reactivity to two adjacent epitopes of the neuraminidase protein. The differential serum IgG recognition was focused on haemagglutinin 1 (H1) and restricted to classical antigenic sites (Cb) in both the vaccinated controls and individuals with flu infections. We further identified a novel epitope VEPGDKITFEATGNL on the Ca antigenic site (251–265) of the pandemic flu haemagglutinin, which was exclusively recognized in serum from individuals with previous vaccinations and never in serum from individuals with H1N1 infection (confirmed by RNA PCR analysis from nasal swabs). This epitope was mapped to the receptor‐binding domain of the influenza haemagglutinin and could serve as a correlate of immune protection in the context of pandemic flu. The study shows that unbiased epitope mapping using peptide microarray technology leads to the identification of biologically and clinically relevant target structures. Most significantly an H1N1 infection induced a different footprint of IgG epitope recognition patterns compared with the pandemic H1N1 vaccine.     

Immune Reactivity to GAD25 in Type 1 Diabetes Mellitus

While both isoforms of glutamic acid decarboxylase (GAD) function as important autoantigens in autoimmune diabetes mellitus--GAD65 in humans and GAD67 in the NOD mouse--GAD67 is not synthesized in human pancreatic islets and is thought not to be an autoantigen in human diabetes. We have recently shown, however, that human islets contain a GAD67 splice variant: GAD25. Given the evidence that GAD67 could be a key diabetogenic autoantigen in the NOD mouse and the high prevalence of GAD65 autoantibodies in human type 1 diabetes, it became important to ask whether there is also immune reactivity to GAD25 in type 1 diabetes--possibly implicating it in the pathogenesis of the disease--and whether GAD25 reactivity could, like GAD65 reactivity, function as a clinically useful marker for the disease. We also hypothesized that the presence of autoantibodies to the smaller splice variant could be a cause of the up to 30% prevalence of GAD67 autoreactivity associated with type 1 diabetes. We therefore analyzed GAD25 reactivity in 105 newly-diagnosed children with type 1 diabetes and 74 control subjects. While 14 (13%) of the diabetic subjects were positive for GAD67 autoantibodies, only 3 (3%) were positive for GAD25 reactivity, none of which were GAD67 antibody-positive. Analysis of reactivity to a GAD67 chimera was consistent with GAD67 binding activity being due to cross-reactive GAD65 antibodies. Immunostaining confirmed the presence of GAD25 in human islets, revealing GAD25-positive cells to be sparse. Our results indicate that autoreactivity to GAD25 is rare in newlydiagnosed type 1 diabetes and does not underlie GAD67 reactivity.     

Idiotype regulation of thymus autoantibodies.

Rabbit antisera specific for idiotypic determinants (Id) of monoclonal Thy-1 autoantibodies were tested for their capacity to elicit Id-bearing thymus autoantibodies in mice. Rabbits were immunized with the 20-10-5 monoclonal IgM Thy-1 autoantibody, and idiotype-specific antibodies (anti-Id) were obtained by affinity chromatography. BALB/c and C3H mice were immunized by repeated i.p. injections of the anti-Id reagent. Control mice received repeated injections of purified normal rabbit immunoglobulin (NRIg) sheep red blood cells (SRBC) or human serum albumin (HSA). The sera of the treated mice were examined for their reactivity with anti-Id xenoantisera and for their capacity to react with thymus cells. The injection of anti-Id sera into either BALB/c or C3H mice resulted in a significant increase in the serum concentration of Id-bearing immunoglobulins, while no such change was observed in the sera of mice injected with NRIg. The administration of anti-Id, NRIg, SRBC or HSA resulted in a gradual increase in the concentration of autoantibodies reactive with thymus cells. Incubation with anti-Id sera prevented the binding to thymus cells of autoantibodies induced by anti-Id treatment. In contrast, the binding capacity of autoantibodies induced by NRIg, SRBC or HSA was unaffected by anti-Id sera. Thus, only the thymus autoantibodies induced by anti-Id treatment expressed Id-determinants. These results demonstrate the existence of a regulatory network in the formation of thymus autoantibodies.     

Antiribonuclease H2 antibodies are an immune biomarker for systemic lupus erythematosus

We previously reported that autoantibodies against the proliferating cell nuclear antigen protein (PCNA)-binding protein chromatin assembly factor-1 (CAF-1) are specifically found in patients with systemic lupus erythematosus (SLE). PCNA and its complex constituents elicit autoimmune responses in patients with SLE, suggesting that autoantibody diversification likely occurs owing to epitope spreading. Therefore, we sought to clarify whether patients with SLE exhibit an autoimmune response to Ribonuclease H2 (RNase H2), another PCNA-binding protein that regulates cell division. As results, RNase H2 autoantibodies were detected in the sera of 33.9% (19/56) of SLE patients, which was significantly higher than that observed in sera from other patients with systemic autoimmune diseases (polymyositis/dermatomyositis, systemic sclerosis, Sjogren’s syndrome, mixed connective tissue disease and rheumatoid arthritis) and healthy controls. Regression analysis also showed that serum anti-RNase H2 levels were strongly correlated to that of CAF-1 in SLE patients. Our data support the use of RNase H2 autoantibodies as a serum biomarker for SLE diagnosis. Moreover, the strong correlation observed between RNase H2 and CAF-1 suggests that intermolecular epitope spreading may play a critical role in autoantibody production and diversification in SLE.     

Increased IL-17A secretion in response to Candida albicans in autoimmune polyendocrine syndrome type 1 and its animal model

Autoimmune polyendocrine syndrome type 1 (APS-1) is a multiorgan autoimmune disease caused by mutations in the autoimmune regulator (AIRE) gene. Chronic mucocutaneous candidiasis, hypoparathyroidism and adrenal failure are hallmarks of the disease. The critical mechanisms causing chronic mucocutaneous candidiasis in APS-1 patients have not been identified although autoantibodies to cytokines are implicated in the pathogenesis. To investigate whether the Th reactivity to Candida albicans (C. albicans) and other stimuli was altered, we isolated PBMC from APS-1 patients and matched healthy controls. The Th17 pathway was upregulated in response to C. albicans in APS-1 patients, whereas the IL-22 secretion was reduced. Autoantibodies against IL-22, IL-17A and IL-17F were detected in sera from APS-1 patients by immunoprecipitation. In addition, Aire-deficient (Aire(0/0) ) mice were much more susceptible than Aire(+/+) mice to mucosal candidiasis and C. albicans-induced Th17- and Th1-cell responses were increased in Aire(0/0) mice. Thus an excessive IL-17A reactivity towards C. albicans was observed in APS-1 patients and Aire(0/0) mice.