Analysis of in vivo role of alpha-fodrin autoantigen in primary Sjogren's syndrome

The alpha-fodrin N-terminal portion (AFN) autoantigen mediates in vivo immunoregulation of autoimmune responses in primary Sj?gren's syndrome (SS). We further examined this process and found that cleavage products of AFN were frequently detected in the salivary gland duct cells of SS patients. In in vitro studies using human salivary gland HSY cells, anti-Fas-induced apoptosis resulted in specific cleavage of alpha-fodrin into the 120-kd fragment, in association of alpha-fodrin with mu-calpain, and activation of caspase 3. Significant proliferative responses against AlphaFN autoantigen were observed in the peripheral blood mononuclear cells (PBMCs) from SS patients with higher pathological score (grade 4) and with short duration from onset (within 5 years). In vivo roles of AFN peptides were investigated using PBMCs from patients with SS, systemic lupus erythematosus, and rheumatoid arthritis. Significant proliferative T-cell responses of PBMCs to AFN peptide were detected in SS but not in systemic lupus erythematosus or rheumatoid arthritis. AFN peptide induced Th1-immune responses and accelerated down-regulation of Fas-mediated T-cell apoptosis in SS. Our data further elucidate the in vivo role of AFN autoantigen on the development of SS and suggest that the AFN autoantigen is a novel participant in peripheral tolerance.     

Identification of tear lipocalin as a novel autoantigen target in Sjögren's syndrome

Sj?gren's syndrome (SS) is an autoimmune disease characterized by lymphocytic infiltration and tissue damage mainly confined to the salivary and lacrimal glands, resulting in dryness of mouth and eyes. Since different epithelial cells of exocrine and non-exocrine tissues are primarily affected, an autoimmune reaction against antigens commonly expressed in epithelial cells is believed to play a pathogenic role. To identify novel autoantigen targets associated with the systemic involvement in SS, we screened a random peptide library with pooled IgG immunoglobulins derived from patients with primary SS. Among the identified peptides, one was recognized by the majority of patients' sera, but not by sera of normal donors and of patients with other autoimmune diseases. The peptide showed homology with an Epstein-Barr Virus (EBV) derived protein and with tear lipocalin, a protein highly expressed in tears and saliva, and with alpha-fodrin, a cytoskeleton protein considered an important autoantigen target in SS. Anti-peptide antibodies affinity purified from patients' sera recognize the viral protein, tear lipocalin and alpha-fodrin. Our findings suggest that EBV infection may be linked to the pathogenesis of SS and that tear lipocalin can be considered a novel and yet unidentified autoantigen in SS.     

Immunoglobulin isotype profile of tissue transglutaminase autoantibodies is correlated with the clinical presentation of coeliac disease

Coeliac disease (CD) is characterized by the appearance of autoantibodies against tissue transglutaminase (tTG-Ab). Immunoglobulin A (IgA) tTG-Ab have been described as excellent diagnostic markers, but the Ig subclass distribution and the importance of isotype tTG-Ab have not yet been established. In this study, using newly developed isotype- and subclass-specific radioligand assays, we examined anti-tTG IgA1, IgA2, IgG1, IgG4 and IgE antibodies in 30 symptomatic, untreated patients with CD and 22 subjects suspected to suffer from silent CD (sCD). Among 30 patients with CD, 27 (90.0%) were positive for IgA1 tTG-Ab, whereas only 12 (40.0%) had autoantibodies of the IgA2 subclass (P <0.001). IgG1, IgG4 and IgE tTG-Ab were detected in 17 (56.6%), 0 and 3 (10.0%) individuals, respectively. IgA1 was also the predominant anti-tTG subclass in patients with sCD (n=20, 90.1%), followed by IgA2 antibodies (n=7, 31.8%), IgG1 antibodies (n=4, 18.2%), IgG4 antibodies (n=1, 4.5%) and IgE antibodies (n=1, 4.5%). The comparison between both groups revealed a significantly higher prevalence of IgG1 antibodies in patients with symptomatic CD (P <0.01). In 10 of 11 subjects undergoing an intestinal biopsy, the diagnosis of an sCD was confirmed. In this subgroup, there was a positive association between the presence of IgA2 and IgG1 tTG-Ab and severe (Marsh 2-3) mucosal abnormalities. In conclusion, patients with symptomatic and sCD predominantly have IgA1 tTG-Ab. IgG1 tTG-Ab are associated with symptomatic disease and, when present in patients with sCD, are correlated with a severe mucosal destruction. These data suggest that tTG-Ab subclasses could reflect inflammatory events associated with epithelial destruction.     

Increased serum levels of IgA1-IgG immune complexes and anti-F(ab')2 antibodies in patients with primary IgA nephropathy

A solid-phase ELISA was used to detect IgA1 immune complexes (IgA1 ICs) containing IgG and IgM in 38 serum samples from 30 patients with primary IgA nephropathy (IgAN) and 14 subjects with non-IgA chronic glomerulonephritis. A jackfruit lectin, jacalin, was used as the substrate for the selective binding of human IgA1 ICs in serum PEG precipitate (7%). The presence of IgG, A and M antibodies against the F(ab')2 region of IgG was also investigated by the solid-phase ELISA. Six patients were studied during remission and relapse (fever, upper respiratory tract infection and macroheamaturia). The results showed significant increases in serum levels of IgA1 ICs (P less than 0.001) in 39.4% of the IgAN patients, IgA1-IgG ICs (P less than 0.001) in 68.4%, and IgA1-IgM ICs (P less than 0.002) in 10.5% of the patients. A significant increase in IgA1-IgG ICs was observed during relapse (P less than 0.02). Significantly high values of IgG (P less than 0.003) and IgA (P less than 0.001) antibodies directed at the F(ab')2 region of IgG were found. A significant increase in anti F(ab')2 antibodies (class IgA and IgM) was seen in the acute phase of the disease. The data suggest that an increased production of IgA1 ICs occurs in IgAN patients; ICs are mainly IgA1-IgG ICs during relapse. The presence of high serum levels of IgG and IgA antibodies against the F(ab')2 region of IgG indicates that in addition to the multiple anomalies of IgA regulation described in IgAN patients there may be further aberrances.     

Comparison of tissue transglutaminase-specific antibody assays with established antibody measurements for coeliac disease

Tissue transglutaminase C has recently been identified as one of the auto-antigens of endomysial antibodies found in coeliac disease. In this study we have cloned the human autoantigen and developed immunoassays measuring antibodies to transglutaminase in order to compare their diagnostic performance to that of established markers of the disease. A radiobinding assay using in vitro transcribed and translated 35S-methionine-labelled transglutaminase detected IgG antibodies in 110 and IgA antibodies in 109 of 112 patients at diagnosis of coeliac disease and in three and four of 92 control subjects, respectively. A radiobinding assay measuring both IgG and IgA transglutaminase antibodies identified 111 (99.1%) of the patients and 4 (4.3%) control subjects. Concordance of this assay with the IgA endomysial antibody test was found in 108 patients and 89 control subjects: two patients who had IgA deficiency and a third patient without IgA deficiency were only detected in the radiobinding assay; one patient had weak IgA endomysial antibodies only, and three of the control subjects with weak transglutaminase antibodies by radiobinding assay were undetectable in the IgA endomysial antibody assay. IgA and IgG ELISA using guinea pig transglutaminase and commercial ELISA measuring anti-gliadin antibodies had lower sensitivity and specificity than the radiobinding assays or the IgA endomysial antibody assay. This study confirms tissue transglutaminase C as a major autoantigen in coeliac disease and describes novel radiobinding assays for large scale testing to identify cases of coeliac disease.     

Molecular analysis of the human autoantibody response to alpha-fodrin in Sjögren's syndrome reveals novel apoptosis-induced specificity

Lymphocyte infiltration of salivary and lacrimal glands leading to diminished secretion and gland destruction as a result of apoptosis is thought to be pivotal in the pathogenesis of Sj?gren's syndrome (SS). The cytoskeletal protein alpha-fodrin is cleaved during this apoptotic process, and a strong antibody (Ab) response is elicited to a 120-kd fragment of cleaved alpha-fodrin in the majority of SS patients, but generally not in other diseases in which apoptosis also occurs. Little is known about the anti-alpha-fodrin autoantibody response on a molecular level. To address this issue, IgG phage display libraries were generated from the bone marrow of two SS donors and a panel of anti-alpha-fodrin IgGs was isolated by selection on alpha-fodrin immunoblots. All of the human monoclonal Abs (hmAbs) reacted with a 150-kd fragment and not with the 120-kd fragment or intact alpha-fodrin, indicating that the epitope recognized became exposed after alpha-fodrin cleavage. Analysis of a large panel of SS patients (defined by the strict San Diego diagnostic criteria) showed that 25% of SS sera exhibited this 150-kd alpha-fodrin specificity. The hmAbs stained human cultured salivary acinar cells and the staining was redistributed to surface blebs during apoptosis. They also stained inflamed acinar/ductal epithelial cells in SS salivary tissue biopsies, and only partially co-localized with monoclonal Abs recognizing the full-length alpha-fodrin. Our study shows that in SS patients, neoepitopes on the 150-kd cleaved product of alpha-fodrin become exposed to the immune system, frequently eliciting anti-150-kd alpha-fodrin Abs in addition to the previously reported anti-120-kd Abs. The anti-150-kd alpha-fodrin hmAbs may serve as valuable reagents for the study of SS pathogenesis and diagnostic analyses of SS salivary gland tissue.     

Adherence-inhibitory intestinal immunoglobulin a antibody response in baboons elicited by use of a synthetic intranasal lectin-based amebiasis subunit vaccine

We designed an amebiasis subunit vaccine that is constructed by using four peptide epitopes of the galactose-inhibitable lectin heavy subunit that were recognized by intestinal secretory immunoglobulin A (IgA) antibodies from immune human subjects. These epitopes are contained in the region encompassing amino acids 758 to 1134 of the lectin heavy subunit, designated LC3. Baboons (Papio anubis) are natural hosts for Entamoeba histolytica; naturally infected baboons raised in captivity possess serum IgA antibodies to the same four LC3 epitopes as humans. Uninfected, seronegative baboons received four intranasal immunizations at 7-day intervals with the synthetic peptide vaccine (400, 800, or 1,600 mug per nostril) with cholera toxin (20 mug) as the adjuvant. As determined by an enzyme-linked immunosorbent assay (ELISA), each dose of the peptide vaccine elicited antipeptide serum IgA and IgG and intestinal IgA antibody responses in all six immunized baboons by day 28, 7 days after the last immunization (P, <0.01 for each dose compared to the cholera toxin control). The peptide vaccine elicited serum IgG and intestinal IgA antibodies that recognized purified recombinant LC3 protein (P, <0.008 and 0.02, respectively) and native lectin protein (P < 0.01). In addition, an indirect immunofluorescence assay with whole trophozoites (P < 0.01) and Western blot analysis confirmed that serum IgG antibodies from vaccinated baboons recognized native lectin protein on the surfaces of axenic E. histolytica trophozoites or from solubilized amebae. All four synthetic peptides were immunogenic; the vaccine elicited dose- and time-dependent responses, as determined by ELISA optical density readings indicating the production of serum and intestinal antibodies (P, <0.02 for antipeptide and antilectin antibodies). As a positive control, intranasal immunization with purified recombinant LC3 protein with cholera toxin as the adjuvant elicited a serum anti-LC3 IgA and IgG antibody response (P, 0.05 and <0.0001, respectively); however, no intestinal anti-LC3 IgA antibody response was observed (P = 0.4). Of interest, serum IgA and IgG antibodies elicited by the recombinant LC3 vaccine did not recognize any of the four putatively protective LC3 peptide epitopes. Both serum and fecal antibodies elicited by the peptide vaccine exhibited neutralizing activity, as determined by their dose-dependent inhibition of the galactose-specific adherence of E. histolytica trophozoites to Chinese hamster ovary cells in vitro (P, <0.001 for each group of antibodies compared to the control). In summary, a lectin-based intranasal polylysine-linked synthetic peptide vaccine was effective in eliciting an adherence-inhibitory, intestinal antilectin IgA antibody response in baboons. Future studies with the baboon model will determine vaccine efficacy against asymptomatic E. histolytica intestinal infection.     

Anti-calreticulin antibodies and calreticulin in sera of patients diagnosed with dilated or hypertrophic cardiomyopathy

Distinct cellular level of the Ca²⁺-binding chaperone calreticulin (CRT) is essential for correct embryonal cardiac development and postnatal function. However, CRT is also a potential autoantigen eliciting formation of antibodies (Ab), whose role is not yet clarified. Immunization with CRT leads to cardiac injury, while overexpression of CRT in cardiomyocytes induces dilated cardiomyopathy (DCM) in animals. Hence, we analysed levels of anti-CRT Ab and calreticulin in the sera of patients with idiopatic DCM and hypertrophic cardiomyopathy (HCM). ELISA and immunoblot using human recombinant CRT and Pepscan with synthetic, overlapping decapeptides of CRT were used to detect anti-CRT Ab. Serum CRT concentration was tested by ELISA. Significantly increased levels of anti-CRT Ab of isotypes IgA (p?p?p?相似文献   

Humoral immune response to membrane components of Chlamydia trachomatis and expression of human 60 kDa heat shock protein in follicular fluid of in-vitro fertilization patients

Recent evidence suggests that Chlamydia trachomatis can persist in the female upper genital tract in an unculturable state. Since unsuspected C. trachomatis infection has been associated with adverse in-vitro fertilization (IVF) outcome we sought to detect further evidence of C. trachomatis in the genital tracts of women undergoing IVF. The prevalence and distribution of antibodies to the major structural proteins of C. trachomatis in paired follicular fluid and sera of women undergoing IVF were examined. Sera and follicular fluid samples from 149 women were assayed for immunoglobulin (Ig)G and IgA antibodies to two C. trachomatis antigens, the major outer membrane protein (MOMP) and a recombinant lipopolysaccharide (rLPS) fragment. Additionally, the expression of human 60 kDa heat shock protein (hsp 60) in follicular fluid was determined. All cervical and follicular fluid samples were negative for C. trachomatis by polymerase chain reaction, ligase chain reaction and DNA probe. Sera from 60% of the subjects were positive for antichlamydial rLPS IgG; 36% were positive for anti-MOMP IgG. Similarly, rLPS-directed and MOMP-directed IgA were detected in sera of 34 and 14% of the subjects respectively. IgG antibodies to MOMP and rLPS were detected in 42 and 41% of the follicular fluid examined respectively. Anti-MOMP IgA was identified in 8.7% of the follicular fluid while 27.5% were positive for anti-rLPS IgA. Human hsp 60 expression was documented in 11.6% of the follicular fluid tested. IgA antibodies to both MOMP (P = 0.03) and rLPS (P = 0.02) in follicular fluid were associated with a failure to become pregnant after embryo transfer. IgG antibodies in sera and follicular fluid and IgA antibodies in sera were unrelated to IVF outcome. Similarly only anti- MOMP IgA (P = 0.02) and anti-rLPS IgA (P = 0.04) in follicular fluid were correlated with human hsp 60 expression in follicular fluid. The unique association between IgA antibodies to two chlamydial antigens in follicular fluid and both hsp 60 expression and IVF failure provides further support for the possibility that a persistent upper genital tract chlamydial infection contributes to IVF failure in some women.      

Diagnosis of invasive amebiasis by enzyme-linked immunosorbent assay of saliva to detect amebic lectin antigen and anti-lectin immunoglobulin G antibodies

Saliva from subjects with amebic liver abscess (ALA), acute amebic colitis, asymptomatic infection with Entamoeba histolytica or Entamoeba dispar, and uninfected controls was tested by enzyme-linked immunosorbent assay (ELISA) for the presence of E. histolytica galactose-inhibitable lectin antigen and salivary immunoglobulin (IgG) antibodies to a recombinant cysteine-rich lectin-derived protein (LC3). Salivary lectin antigen was found in 65.8% of subjects with acute colitis, compared to 22.2% of those convalescent from ALA, 10.0% with asymptomatic E. histolytica infection, 9.8% with E. dispar infection, and 2.6% of controls (subjects from the United States and study patients with nonamebic diarrhea) (P < 0.001 for each compared to values for subjects with colitis). Salivary anti-LC3 IgG antibodies were found in 92% of ALA patients regardless of duration of illness and in 83.3% of colitis patients who were symptomatic for at least 7 days (P < 0.001 compared to other study groups). Serum anti-LC3 IgG antibodies were detected in 56.3% of subjects with acute colitis, 100% of subjects with ALA or prolonged colitis, 45% of subjects with asymptomatic E. histolytica infection, 32.3% of subjects with E. dispar infection, and 23.4% of diarrhea controls. In comparison to ELISA for serum anti-LC3 IgG antibodies, the salivary lectin antigen assay is a more sensitive and specific test for acute amebic colitis. Detection of salivary anti-LC3 IgG antibodies by ELISA is an effective means for the diagnosis of ALA and prolonged cases of amebic colitis.     

Immunoglobulin G (IgG) Anti-Tissue Transglutaminase Antibodies Used as Markers for IgA-Deficient Celiac Disease Patients

The role of immunoglobulin A (IgA) anti-tissue transglutaminase antibodies (IgA-tTG) as predictors of untreated celiac disease (CoD) is well documented, and the presence and levels of these antibodies are most accurately monitored with native or recombinant human antigens. However, IgA-deficient CoD patients are not identified by IgA serology, and conflicting results concerning the diagnostic validity of IgG antibodies against gliadin (IgG-AGA), endomysium (IgG-EmA), and tTG (IgG-tTG) have been reported. The aim of the present study was to evaluate the utility of IgG-tTG for the detection of CoD in IgA-deficient patients. Samples from 115 IgA-deficient and 200 IgA-sufficient subjects were collected and tested for the presence of IgA and IgG antibodies against tTG, EmA, and AGA. Antibodies against tTG were measured by an enzyme-linked immunosorbent assay based on recombinant human tTG, and antibodies against EmA were determined by immunofluorescence. The values for IgG-tTG showed a higher correlation (correlation coefficient [r] = 0.91) with those for IgG-EmA for the IgA-deficient subjects than for the IgA-sufficient subjects (r = 0.88). The overall concordance of the positive and negative results between IgG-tTG and IgG-EmA was 97%, and the IgG-tTG assay discriminated between IgG-EmA-positive and -negative subjects with IgA deficiency at a rate of 100%. Elevated levels of IgG-tTG and IgG-EmA were measured in 70% of the IgA-sufficient subjects. IgG-tTG detection with recombinant human tTG is a good alternative to IgG-EmA detection, and the addition of IgG-tTG assessment to present screening methods may improve the ability to identify IgA-deficient subjects with CoD.     

Involvement of apoptotic protease cascade for tissue destruction in Sjögren's syndrome

Sj?gren syndrome (SS) is an autoimmune disease characterized by diffuse lymphoid cell infiltrates in the salivary and lacrimal glands, resulting in symptoms of dry mouth and eyes due to insufficient secretion. Although it has been assumed that a combination of immunologic, genetic and environmental factors may play a key role in the development of autoimmune lesions in the salivary and lacrimal glands, little is known about the disease pathogenesis of SS in humans. We have identified the 120 kDa alpha-fodrin as an important autoantigen in the development of SS in both an animal model and SS patients, but the mechanism of alpha-fodrin cleavage leading to tissue destruction in SS remains unclear. Tissue-infiltrating CD4+ T cells purified from the salivary glands of a mouse model for SS bear a large proportion of Fas ligand and the salivary gland duct cells possess apoptotic receptor Fas. Anti-Fas antibody-induced apoptotic salivary gland cells result in specific alpha-fodrin cleavage to the 120 kDa fragment in vitro. Preincubation with a combination of calpain and caspase inhibitor peptides could be responsible for inhibition of the 120 kDa alpha-fodrin cleavage. Thus, an increase in apoptotic protease activities including calpain and caspases may be involved in the progression of alpha-fodrin proteolysis and tissue destruction in the development of SS.     

Immunoglobulin G, A, and M responses to BK virus in renal transplantation

Immunoglobulin G (IgG), IgA, and IgM antibodies were measured in serum samples from 71 organ donors, 81 kidney transplant recipients at transplantation, and 67 patients during the posttransplant period by using a virus-like particle-based enzyme-linked immunosorbent assay (ELISA). BK virus (BKV) and JC virus DNA were detected in urine and plasma by real-time PCR. IgG antibodies to BKV were demonstrated in the majority (80.3 to 100%) of patients irrespective of clinical category, but titers were highest in patients with active viral replication. IgA antibodies were present with greater frequency (72.7 to 81.3% versus 0 to 23.6%; P < 0.001) and higher titer (mean optical density, 0.11 to 0.15 versus 0.05 to 0.08; P < 0.001) in patients who were BKV DNA positive than those who were BKV DNA negative. IgM antibodies showed a similar pattern of reactivity but lower frequency in the setting of active viral replication (9.1 to 43.7% versus 0 to 1.4%; P < 0.001). A rise in IgG level of >0.577 optical density (OD) units or a rise in IgA or IgM level of >0.041 OD units was strongly associated with active viral replication. Urine viral load showed a positive correlation with IgM titer (r = 0.22) but a negative correlation with IgG titer (r = -0.28) and IgA titer (r = -0.1). Chronic dialysis patients typically did not have serologic or virologic evidence of active BKV infection. Anti-BKV titers did not rise in patients with JC viruria. In conclusion, measurement of anti-BKV antibody titer and class response can be used to detect the onset of viral replication. ELISAs can be quite specific despite considerable sequence homology between BK virus and JC virus.     

Lipopolysaccharide- and cholera toxin-specific subclass distribution of B-cell responses in cholera.

The immunoglobulin subclass responses to homologous lipopolysaccharide (LPS) and to cholera toxin (CT) in adult patients infected with Vibrio cholerae O1 and V. cholerae O139 were studied. LPS-specific antibody-secreting cells (ASC) of both the immunoglobulin A1 (IgA1) and IgA2 subclasses were seen, with the IgA1 ASC response predominating in both V. cholerae O1- and O139-infected patients. For antibodies in plasma, by day 11 after onset of disease, all V. cholerae O1- infected patients responded to homologous LPS with the IgA1 subclass (P = 0.001), whereas fewer (68%) responded with the IgA2 subclass (P = 0.007). About 89% of V. cholerae O139-infected patients responded with the IgA1 subclass (P = 0.003), and only 21% responded with the IgA2 subclass (not significant [NS]). Both groups of cholera patients showed significant increases in LPS-specific IgG1, IgG2, and IgG3 antibodies in plasma. In feces, the response to homologous LPS occurred in both groups of patients with the IgA1 and IgA2 subclasses, with 55 to 67% of patients showing a positive response. V. cholerae O1- and O139-infected patients showed CT-specific ASC responses of the different IgG and IgA subclasses in the circulation, and the pattern followed the order IgG1 > IgA1 > IgG2 > IgA2, with low levels of IgG3 and IgG4 ASC. Plasma anti-CT antibody responses in all subclasses were seen by day 11 after onset of disease. Although there were no increases in CT-specific ASC of the IgG3 (NS) and IgG4 (NS) subtypes, there were significant increases of these two subclasses in plasma (P 相似文献   

Detection of anti-SS-A/Ro and anti-SS-B/La antibodies of IgA and IgG isotypes in saliva and sera of patients with Sj?gren's syndrome.

To assess the frequency and the possibility of local production of autoantibodies against SS-A/Ro and SS-B/La in patients with primary Sj?gren's syndrome (SS), serum and saliva samples were obtained from 42 patients with SS, 10 with rheumatoid arthritis without sicca syndrome, and 12 healthy volunteers. Autoantibodies were detected using enzyme-linked immunosorbent assay and immunoblotting. The frequencies of IgA anti-SS-A antibody, IgA anti-SS-B antibody, IgG anti-SS-A antibody and IgG anti-SS-B antibody in serum from SS patients were 45%, 50%, 43% and 21%, respectively. The frequencies of IgA anti-SS-A antibody, IgA anti-SS-B antibody, IgG anti-SS-A antibody and IgG anti-SS-B antibody in saliva from SS patients were 31%, 33%, 40%, and 19%, respectively. We also found secretory IgA anti-SS-A and anti-SS-B antibodies accompanying secretory components in saliva and sera in representative SS patients. Significant correlations were found between serum and salivary levels of IgA anti-SS-A antibodies, and between serum and salivary levels of IgA anti-SS-B antibodies in SS patients. Significant correlations were also found between serum and salivary levels of IgG anti-SS-A antibodies, and between serum and salivary levels of IgG anti-SS-B antibodies in SS patients. Immunoblot analysis confirmed the presence of IgA-class autoantibodies against SS-A and SS-B in saliva and serum from representative patients. The presence of IgA- and IgG-class autoantibodies against SS-A and SS-B and those accompanying secretory components in saliva from SS patients suggests the local production of these antibodies and the relationship between local and systemic antibody responses.     

Clinical significance of autoantibodies recognizing Sjögren's syndrome A (SSA), SSB, calpastatin and alpha-fodrin in primary Sjögren's syndrome

The aim of our study was (i) to compare the clinical and biological characteristics of 148 (137 women, 11 men) primary Sjögren's syndrome (pSS) patients at diagnosis as a function of their sex and (ii) to assess the prognostic value of anti‐calpastatin and anti‐alpha‐fodrin autoantibodies. In addition, the presence of anti‐nuclear antibodies (ANA), anti‐52‐ and 60‐kDa Sjögren's syndrome A (SSA), anti‐Sjögren's syndrome B (SSB), anti‐cyclic citrullinated peptide (CCP) antibodies and rheumatoid factors (RF) of IgA, IgG and IgM isotypes was sought in sera collected at pSS onset. Raynaud's syndrome, significantly more frequent in women, was the only systemic manifestation of pSS whose frequency differed significantly as a function of the patient's sex (P = 0·02). ANA (P = 0·001) and anti‐60‐kDa SSA autoantibodies (P = 0·03) were significantly more common in women, while men never synthesized detectable levels of anti‐SSB, anti‐calpastatin or IgG anti‐alpha‐fodrin autoantibodies. In addition, anti‐CCP autoantibodies were found in low percentages of pSS patients (4% F/18% M). The absence of autoantibodies does not exclude the diagnosis of pSS in men that will be based mainly on the anatomopathological findings of a minor salivary gland biopsy. Positivity of anti‐60‐kDa SSA, anti‐SSB, anti‐calpastatin, IgA and IgG anti‐alpha‐fodrin antibodies is not associated with pSS clinical and biological severity.     

Immunoglobulin levels amongst persons with and without human immunodeficiency virus type 1 infection in Uganda and Norway

CD4+-cell count and viral load monitoring are expensive and unavailable to most human immunodeficiency virus (HIV)-infected people in Africa. In an attempt to evaluate alternative methods for monitoring antiretroviral (ARV) therapy, we measured concentrations of immunoglobulin (Ig)A, IgM, IgG and IgG1 amongst adults with and without HIV in Uganda and Norway. We adjusted for disease severity by stratifying HIV-positive subjects on CD4+-cell counts above and below 200 cells/ micro l. Median serum levels of IgG, IgG1 and IgA were significantly higher in HIV-positive persons compared with HIV-negative persons in both countries (P < 0.001 and P = 0.018 for IgA in Ugandan patients). Levels of IgA in Ugandan HIV-negative subjects were significantly lower than those in HIV-positive subjects with low CD4+ compared with those with high CD4+-cell counts (P < 0.001 and P = 0.069, respectively). IgM levels were different between the HIV-negative and the two HIV-positive groups in Norway (P < 0.001). The mean levels of IgM, IgG and IgG1 in HIV-negative and -positive African subjects were generally higher than those in comparable groups of Western subjects. Our results verify that levels of IgA, IgG and IgG1 vary between HIV-negative and -positive individuals in both study populations. Their determination may be useful in monitoring both disease progression and response to ARV therapy.     

Humoral immune response in human tuberculosis: immunoglobulins G, A, and M directed against the purified P32 protein antigen of Mycobacterium bovis bacillus Calmette-Guérin

The P32 protein antigen of Mycobacterium bovis BCG, identified as antigen 85A in the BCG reference system, was used to investigate the humoral immune response in human tuberculosis (TB). Immunoglobulin G (IgG), IgA, and IgM directed against P32 were measured by an enzyme-linked immunosorbent assay. Mean IgG and IgA antibody levels differed significantly (P less than 0.001) between active-TB patients (50 untreated and 52 treated) and healthy control subjects (111 unvaccinated tuberculin negative, 38 unvaccinated tuberculin positive, and 72 recently BCG vaccinated). Mean IgG antibody levels, but not mean IgA antibody levels, were higher (P less than 0.05) in patients with positive microscopic examination for acid-fast bacilli than in patients with negative microscopic examination. A positive relation was found between mean levels and the extent of disease. There was no difference in mean IgM antibody levels between patients and controls. By setting the upper normal limit at the 95th percentile of the 221 healthy subjects, the sensitivities were 46% in untreated and 63% in treated patients for IgG and 30 and 50%, respectively, for IgA. Of the untreated patients, 56% were positive for either IgG or IgA antibodies. Among the untreated patients with negative direct smear, 35% were positive for IgG and 24% were positive for IgA. When both immunoglobulin classes were combined, the serological test was positive in 47% of those patients. Neither naturally acquired tuberculin hypersensitivity nor BCG vaccination affected positivity frequencies in healthy subjects. Only active TB seemed to induce significant anti-P32 antibody levels and to be associated with positivity. A serological test with P32 as the antigen might therefore be helpful for the rapid diagnosis of TB.     

Tissue transglutaminase autoantibodies in patients with IgM rheumatoid factors

The recent identification of tissue transglutaminase (tTG) as the autoantigen for celiac disease-associated anti-endomysial antibodies (EMA) has allowed the use of rapid immunoassay to detect the presence of autoantibodies, anti-tTG, in the serum of patients. In this study, we examined the prevalence of IgG or IgA anti-tTG in sera from patients with elevated levels of IgM rheumatoid factors, which are autoantibodies reactive with the Fc portion of IgG. We report here on four cases of anti-tTG positivity for patients with elevated IgM rheumatoid factor (RF) without evidence of celiac sprue. The study population consisted of 65 patients (26 men, 39 women; mean age, 49 years; range 4 - 92 years) with elevated RF (>20 U/ml ), and 23 healthy subjects (12 men, 11 women; mean age, 46 years; range, 21 - 54 years). IgG and IgA anti- tTG levels were detected using a commercially available ELISA kit (Immuno-Biological Laboratories, Germany). Out of 65 patients, one (1.5%) and three (4.6%) patients were positive for IgG and IgA anti-tTG antibodies, respectively, and this was a higher frequency than occurred in healthy subjects (0/23). The clinical features of the four cases positive for IgG or IgA anti-tTG were as follows: The first case (female, 63 yrs) positive for IgA anti-tTG antibody suffered from rheumatoid arthritis, type II diabetes mellitus, iron deficiency anemia and gastric indigestion without symptoms of malabsorption. She denied any gluten sensitivity on her diet. Her esophagogastroduodenoscopic biopsy showed mucosal atrophy with no elongated crypts or infiltration of inflammatory cells in the lamina propria. The remaining three cases positive for anti-tTG antibodies had interstitial pneumonia, a herniated lumbar disc, and mild scoliosis, respectively. They all denied any malabsorption symptoms or gluten sensitivity. Jejunal biopsy could not be performed in all four cases.     

Isotype distribution and clinical relevance of anti-beta2-glycoprotein I (beta2-GPI) antibodies: importance of IgA isotype.

The aim of this study was to evaluate the prevalence of IgG, IgA and IgM anti-beta2-GPI antibodies in anti-phospholipid syndrome (APS), and to establish the clinical significance of IgA type antibodies compared with the other isotypes. Anti-beta2-GPI antibodies were measured in the sera of 70 patients by solid-phase enzyme immunoassay in gamma-irradiated polystyrene plates coated with human purified beta2-GPI. Thirty-three out of the 70 patients were classified as having APS: three of them had primary, and 30 had secondary APS related to systemic lupus erythematosus (SLE). The remaining 37 patients had SLE without APS. Anti-beta2-GPI antibodies of IgG, IgA and IgM isotypes were present in 84.8%, 59.3% and 51.5% of patients with APS. Both the frequency and the level of each isotype were significantly higher in patients with APS. This association was very strong for IgA (P = 0.0004 for the antibody frequency and P < 0.0001 for the antibody level), as well as for IgG type antibodies (P < 0.0001 and P < 0.0001), whereas it was weaker for IgM (P = 0.01 and P = 0.04). A strong relationship was demonstrated between increased IgA anti-beta2-GPI antibody levels and a history of venous thrombosis, thrombocytopenia, heart valve disease, livedo reticularis and epilepsy. IgG anti-beta2-GPI antibodies were associated with the presence of lupus anticoagulant (LA) in addition to the main features of APS. However, antibodies of IgM isotype were related only to thrombocytopenia and heart valve disease. We recommend the evaluation of anti-beta2-GPI antibodies of IgA isotype in addition to IgG in patients with clinical suspicion of APS.