Anti-beta2 glycoprotein I and anticardiolipin antibodies in leptospirosis, syphilis and Kala-azar

OBJECTIVE: Reports have shown that anticardiolipin (aCL) antibodies present in patients with autoimmune diseases are dependent on the cofactor,beta2 glycoprotein I (beta2 GPI), as opposed to aCL antibodies seen in infectious diseases such as syphilis, HIV hepatitis C, etc. The assay for anti-beta2GPI antibodies has been reported to be more specific for antiphospholipid syndrome (APS). However, the prevalence of these antibodies in diseases such as leishmaniasis and leptospirosis remains unknown. The aim of the present study was determine the prevalence of antibodies to cardiolipin and to beta2GPI in patients with different infectious diseases, including leptospirosis, syphilis and leishmaniasis. METHODS: Samples from patients with Kala-azar (visceral leishmaniasis), syphilis or leptospirosis were tested for IgG and IgM anticardiolipin and IgG anti-beta2GPI antibodies by ELISA. RESULTS: In patients with Kala-azar the prevalence of IgG aCL, IgM aCL and anti-beta2GPI was 6% (2/30), 3% (1/30) and 53% (16/30), respectively. In syphilis the prevalence was 18% (14/74), 13% (10/74) and 10% (8/70), respectively. In leptospirosis the frequency of these antibodies was 23% (9/39), 10% (4/39) and 17% (6/34), respectively. There was no statistical correlation between aCL and anti-beta2GPI antibodies in these diseases. DISCUSSION: This study clearly shows a significant prevalence of anti-beta2GPI antibodies in leptospirosis and leishmaniasis and syphilis. This indicates that the assay for antibeta2GPI antibodies should be thoroughly validated before it is introduced as a definitive tool for the diagnosis of APS, testing a larger number of sera from patients with a wider range of clinical conditions.     

Introduction of a rapid dipstick assay for the detection of Leptospira-specific immunoglobulin m antibodies in the laboratory diagnosis of leptospirosis in a hospital in Makassar, Indonesia

An easy, rapid and robust dipstick assay for detection of leptospira-specific immunoglobulin M (IgM) antibodies was evaluated on 403 patients admitted for hospitalization because of fever. The clinical symptoms and signs of 35 patients were consistent with leptospirosis. The final diagnosis for the remaining patients was as follows: 136 with typhoid fever, 82 with hepatitis, 74 with malaria, 48 with infections of the respiratory tract, and 20 with fever of unknown origin. The clinical diagnosis of leptospirosis was confirmed for 24 (68.6%) patients by the combined results of the microscopic agglutination test (MAT), the reference test for leptospirosis, and of IgM ELISA, a standard laboratory test for the serodiagnosis of leptospirosis. In addition, serum specimens from 8 (2.2%) patients with a final clinical diagnosis other than leptospirosis were found to be positive in MAT and/or IgM ELISA. Compared with the results of MAT and IgM ELISA a sensitivity of 91.6% and specificity of 93.6% was calculated for the dipstick assay. Most of the serum samples from the laboratory confirmed patients gave a moderate to strong staining intensity of the antigen band of the dipstick and were easy to read. The results demonstrate that the dipstick assay is convenient to use and allows the rapid and accurate confirmation of patients with clinical suspicion of leptospirosis in areas where the disease is endemic.     

Platelet autoantibodies (IgG,IgM, IgA) against glycoproteins IIb/IIIa and Ib/IX in patients with thrombocytopenia

 Autoimmune thrombocytopenic purpura (AITP) is most frequently induced by platelet-specific autoantibodies against epitopes on platelet GP Ib/IX or GP IIb/IIIa. These antibodies are reliably detected on the patients' autologous platelets. So far, studies on the characterization of platelet autoantibodies have been restricted to IgG antibodies. We used the monoclonal antibody immobilization of platelet antigens assay (MAIPA) in a modified version to detect GP-specific IgG, IgM, and IgA antibodies. Platelets of 46.2% of patients carried elevated amounts of IgG antibodies. IgM and IgA antibodies were observed less frequently and showed only weak OD signals in the MAIPA assay. Circulating IgG antibodies in serum were found in 11.5% of patients. Circulating IgM autoantibodies were observed in 8.9% and IgA antibodies in no patient with AITP. Results of direct MAIPA assay were compared with the reactivity of eluates in the platelet adhesion immunofluorescence assay and were found to be highly concordant. Patients with AITP in remission carried high percentages of anti-GP IIb/IIIa. Findings made in this study suggest that autoantibodies of the IgM and IgA classes play only a minor role in the pathogenesis of AITP. Received: 14 December 1995 / Accepted: 24 January 1996     

Antibodies to recombinant human tissue-transglutaminase in coeliac disease: Diagnostic effectiveness and decline pattern after gluten-free diet

BACKGROUND/AIMS: To assess the sensitivity and specificity of IgA and IgG tissue-transglutaminase antibodies assay, the pattern of antibody decline after gluten withdrawal and their modifications with reference to dietary compliance. SUBJECTS: We studied sera from 143 untreated coeliac children and adolescents (8.8+/-6.1 years), 212 sera from 97 of those patients after gluten withdrawal, and 64 control subjects with non-coeliac intestinal disorders (6.8+/-4.8 years). METHODS: Samples were tested for IgA and IgG class tissue-transglutaminase antibodies by radiobinding assay, using human-derived tissue-transglutaminase, and for IgA anti-endomysium antibodies by indirect immunofluorescence on monkey oesophagus. RESULTS: Untreated coeliac patients had significantly higher titres of IgA and IgG tissue-transglutaminase antibodies than controls (p<0.00001); the diagnostic sensitivity was 95.8% and 99.3%, respectively, and the specificity was 95.3%. Three patients with selective IgA deficiency were positive for IgG tissue-transglutaminase antibodies. The concordance rate between IgA tissue-transglutaminase antibodies and anti-endomysium antibodies was 98.1%. Patients on gluten-free diet showed a significant decrease in IgA and IgG tissue-transglutaminase antibodies with respect to untreated patients (p<0.0001). Tissue-transglutaminase was more sensible than anti-endomysium antibodies to detect small amounts of gluten intake when the compliance was poor. CONCLUSIONS: The recombinant human tissue-transglutaminase antibodies assay is a highly sensitive and specific test for diagnosis of coeliac disease, and it is useful in monitoring the compliance to gluten-free diet.     

Underrecognition of leptospirosis during a dengue fever outbreak in Hawaii, 2001-2002

During the 10-year period from 1997 through 2006, the reported mean annual incidence rate of leptospirosis in the state of Hawaii was 3.3/100,000 with a range of 22-60 infections reported each year. Because the clinical presentation is highly variable, however, leptospirosis illness is challenging to recognize and may be underdiagnosed. To assess whether the incidence may be substantially higher than reported figures indicate, we retrospectively studied the prevalence of anti-Leptospira IgM antibodies among specimens obtained over a 12-month period (May 2001 to April 2002) from patients presenting with febrile illness during a dengue fever outbreak in Hawaii. Of 1206 patients testing negative or indeterminate for dengue, 54 (4.5%; 95% confidence interval: 3.3%-5.7%) were positive for anti-Leptospira IgM antibodies using a commercially available dipstick enzyme-linked immunosorbent assay (ELISA). The most common clinical symptoms reported by laboratory-positive leptospirosis patients were fever (92%), headache (88%), and myalgia (83%). Three clinical symptoms were significantly less common among persons laboratory positive for leptospirosis when compared with the 122 patients who had been diagnosed with dengue fever during the outbreak: rash (p < 0.0001), chills (p = 0.05), and petechiae (p = 0.0005). Laboratory-positive leptospirosis infections were identified in persons exposed on each of the 5 most populous islands and illness onsets spanned a 10-month period, reflecting an endemic pattern of disease. If added to the figures obtained via routine passive surveillance, the number of leptospirosis infections identified through this study would more than double the annual incidence rate for Hawaii during 2001. These findings indicate that many leptospiral infections in Hawaii go undiagnosed. Physicians should maintain a high index of suspicion for leptospirosis when assessing patients presenting with acute febrile illness among residents and visitors to Hawaii.     

The clinical significance of specific IgA antibodies in local secretions in cases with chlamydial urogenital infections--comparison with serum antibodies and analysis of antigen specificity by immunoblotting assay]

IgA antibody titers to C. trachomatis in local secretions were measured by immunoperoxidase assay (Savyon kit) in male and female cases with various urogenital infections, and the clinical significance of IgA antibody in the local secretion was discussed. In addition, the antigen specificity of the IgA for C. trachomatis in the local secretions was analyzed by immunoblotting assay. 1) In female cases with cervicitis and male cases with urethritis, the positive rate of IgA antibody in their secretions was higher in cases with C. trachomatis antigen than in those without it. In addition, the IgA antibody titers in their secretions tended to be higher than in serum, suggesting that the result reflected a local immune response at the site of infection. 2) In cases with chronic prostatitis, a condition in which detection of antigen at the site of infection was difficult, the positive rate of IgA antibody in prostatic secretion was 23.6%. We confirmed that most of the IgA antibodies in prostatic secretions were of the secretory type. 3) IgA antibodies in secretions reacted to the major outer membrane protein (MOMP) and 60-Kd polypeptides of the outer membrane of C. trachomatis by immunoblotting assay, proving that they were the secretory IgA antibodies specific for C. trachomatis. These results described above confirmed that measurement of IgA antibody titers in local secretions by immunoperoxidase assay and immunoblotting assay was useful for the diagnosis of chlamydial urogenital infections such as chronic prostatitis, which the antigen detection was usually difficult. Examination of IgA antibody in local secretions was considered to be useful for making a correct diagnosis even in cases who were suspected to have C. trachomatis infection but showed negative antigen.     

Serum IgA antibodies to Epstein-Barr virus (EBV) early lytic antigens are present in primary EBV infection

Primary Epstein-Barr virus (EBV) infection is characterized by the presence of IgM antibodies to viral capsid antigen and the absence of antibodies to EB nuclear antigen. Here, using a flow cytometry-based assay, we investigated whether IgA antibodies are a marker for primary infection. Serum IgA antibodies in 15 individuals with primary EBV infection reacted with 15%-55.6% of HH514-16 Burkitt lymphoma cells expressing early lytic antigens (EAs), whereas IgA antibodies in serum samples from 15 healthy EBV-seropositive individuals reacted with 0.02%-2% of cells with EAs (P<.0001). IgA antibodies in primary infection were directed against the Bam Z Epstein-Barr replication activator (ZEBRA) (BZLF1) and diffuse EA (BMRF1) EAs. Thus, IgA antibodies to EBV EAs are produced during primary EBV infection and are likely to be stimulated as a result of lytic EBV replication in mucosal sites. Detection of IgA antibodies to EA may be developed into a diagnostic tool for primary EBV infection.     

International multi-centre evaluation of a dipstick assay for human leptospirosis

A dipstick assay for the detection of Leptospira-specific immunoglobulin M (IgM) antibodies in human sera was evaluated in 27 laboratories in 23 countries. 873 serum samples from 711 patients including 329 laboratory-confirmed leptospirosis case patients, 239 noncase patients and 69 patients with viral infections causing heamorrhagic fever were tested. Relative to the results of the reference leptospirosis test, the sensitivity of the dipstick assay was 84.5% for serum samples collected during the first 10 days of the disease and 92.1% for serum samples collected 10-30 days after the onset of disease. The specificity was 87.5% and 94.4%, respectively. Similar to viral haemorrhagic fevers, leptospirosis may cause bleeding. A small number of serum samples from patients with haemorrhagic viral infections gave a weak (1 +) stain. All other samples were negative. In conclusion, the dipstick assay is sensitive and specific and reacts well with serum samples from patients infected with a range of leptospiral strains. It is also easy to use and does not require special equipment or refrigeration. Therefore the assay is ideal for use in developing countries and rural settings.     

Salivary IgA and serum IgA and IgG antibodies to Candida albicans in HIV-infected subjects

This study sought to determine IgA, IgG antibodies to Candida albicans in whole saliva and serum from HIV-infected patients and to compare them to a group of healthy controls. The study population consisted of 34 HIV-infected individuals free of any other systemic diseases and thirty healthy controls. IgA concentrations in saliva and IgA and IgG concentrations in serum were measured by a micro enzyme-linked immunosorbent assay. No significant differences were observed in salivary and serum IgA antibodies to C. albicans between the two study groups. Serum IgG antibodies were found to be significantly lower in the HIV-infected (P < 0.05). No significant changes were observed in the specific activity of anti-Candida IgA and IgG antibodies in saliva and serum, in both the study groups. The undifferentiated levels of secretory-IgA antibodies to C. albicans in the patients' and the controls' saliva could be an indicator of the high immune response to opportunistic infections of the HIV-infected subjects, a fact that is verified by the lack of oral candidiasis in the patients' group. The low levels of IgG antibodies in the serum of the HIV-infected patients confirm the high immune response of them.     

Kinetic study of antibodies (IgG, IgA) to Chlamydia trachomatis: importance of IgA antibody in screening test for C. trachomatis infection by peptide-based enzyme immunosorbent assay

To assess the importance of only IgA antibody positivity in the peptide-based ELISA (P-ELISA) examination of kinetic behaviors of antibodies (IgA, IgG) to Chlamydia trachomatis, 426 sera from 52 follow-up antigen-positive patients were assayed. In part, a microimmunofluorescence (MIF) test and an immunoblot (IB) assay were also used for confirmation. The results showed that the positivity rates of IgA and IgG antibodies were 82.7 and 96.2%, respectively, at the first testing. One patient had both IgA- and IgG-negative antibodies at the first testing, but this became only IgA-positive and then IgG-positive. The patient was co-infected with Candida albicans and C. trachomatis, and saw a gynecologist for the symptom of itching. Although the major outer membrane protein was negative in IB assay, the results of the MIF test and absorption experiments were positive. MIF titers for IgA and IgG antibodies to C. pneumoniae were <1:8 and 1:32, respectively, at the peak level of P-ELISA. These findings seem to suggest that when only the IgA antibody is detected by P-ELISA, C. trachomatis infection may be present at an early stage, so confirmation via testing for C. trachomatis is needed.     

Circulating complexes containing IgA and fibronectin in patients with primary IgA nephropathy.

IgA antibodies from patients with primary IgA nephropathy bind to collagens I, II, and IV. Here we show that this binding is mediated by the collagen-binding site of fibronectin, which occurs in the circulation in complex with IgA. No antibodies binding directly to collagen were identified. The complexes were isolated by affinity chromatography on gelatin-Sepharose and heparin-Sepharose, both with affinity for fibronectin, followed by adsorption to anti-human IgA immobilized on agarose gel. The presence of fibronectin and IgA antibodies in the isolated complexes is shown by enzyme-linked immunosorbent assay, gel electrophoresis, and electrophoretic transfer followed by immunostaining. The presence of an IgA-fibronectin complex in serum and the binding of this complex to collagen demonstrate the necessity of removing fibronectin from serum prior to identifying anti-collagen antibodies.     

IgG and IgA antibodies to the collagen-like region of C1q in rheumatoid vasculitis

We investigated the presence of IgG and IgA antibodies to C1q in serum samples from 80 patients with rheumatoid arthritis (RA), 31 patients with rheumatoid vasculitis, and 80 healthy controls. IgG and IgA antibodies to C1q, as measured by enzyme-linked immunosorbent assay, were found in less than 5% of the sera from RA patients and from healthy controls. In contrast, IgG and IgA antibodies to C1q were found in 29% and 61%, respectively, of the sera from patients with rheumatoid vasculitis. The occurrence of IgA antibodies to C1q has not been previously demonstrated. These results also demonstrate that IgG antibodies to C1q do not occur exclusively in systemic lupus erythematosus patients: Sera of patients with rheumatoid vasculitis frequently contain IgG or IgA antibodies to C1q, which contribute to immune complex formation.     

Field evaluation of a one-step dipstick assay for the diagnosis of human leptospirosis in the Seychelles

OBJECTIVE AND METHOD: To compare the response of a dipstick assay (DSA) detecting Leptospira-specific immunoglobulin M (IgM) antibodies with that of an enzyme-linked immunosorbent assay (ELISA), an indirect haemagglutination assay (IHA), the microagglutination test (MAT) and a polymerase chain reaction assay (PCR) in patients with leptospirosis confirmed by MAT alone or by MAT and/or PCR (MAT/PCR). RESULT: In 75 patients with acute leptospirosis diagnosed by MAT (respectively, 90 patients diagnosed by MAT/PCR), the response in paired early and convalescent sera was positive in 78.9% (67.9%) by DSA, 76.0% (67.8%) by ELISA, 58.7% (55.6%) by IHA, 44.0% (53.3%) by PCR, and 100% (90.0%) by MAT. In early serum only, the response in patients diagnosed by MAT (respectively by MAT/PCR) was positive in 36.0% (38.9%) by DSA, 36.0% (37.8%) by ELISA, 14.7% (18.9%) by IHA, 39.2% (48.3%) by PCR, and 53.3% (58.9%) by MAT titre > or =1:100. DSA detected the main serogroups implicated in human leptospirosis in Seychelles and demonstrated sensitivity comparable to ELISA. In 124 single sera from control subjects without overt disease, the response was positive in 4.8% by DSA, 3.2% by ELISA, 3.2% by IHA, 13.8% by PCR, 37.9% by MAT titre > or =1:100, and 2.4% by MAT titre > or =1:800, giving evidence of the frequency of both past and current subclinical infection in Seychelles and that DSA was less sensitive than MAT to detect moderate levels of leptospiral antibodies. CONCLUSION: DSA is a simple and reproducible assay well adapted to field conditions and could usefully contribute to the evaluation of leptospirosis in areas devoid of serological laboratory facilities.     

Weak Anti-IgA Antibodies with Limited Specificity and Nonhemolytic Transfusion Reactions

Anti-IgA antibodies were studied in sera from patients with nonhemolytic transfusion reactions for which no serological reason had been found. Of the 158 sera that were studied by passive hemagglutination assay using twelve IgA myeloma proteins, 4 samples had class-specific antibodies and 10 samples antibodies with limited specificity. Titers were 1:8 or less. 100 multitransfused hemophilia patients were studied with two IgA myeloma proteins. Four of the sera had anti-IgA antibodies. Normal blood donor sera reacted with IgA only when antigens were first either digested with pepsin or stored for several months as dilute solutions in refrigerator. The results emphasize the need for fresh IgA proteins of good quality when human anti-IgA antibodies are investigated.     

An urban outbreak of leptospirosis in Mumbai,India

An outbreak of leptospirosis occurred during the rainy season in the city of Mumbai, India. Out of 169 suspected cases, 74 (43.7%) were determined serologically positive by microagglutination test (MAT) carried out with a battery of eight pathogenic serovars, while 78 (46.1%) were shown positive for IgM antibodies to leptospira by enzyme-linked immunosorbent assay. On the basis of MAT, serovar Copenhageni accounted for 66 (89.1%) out of the 74 cases admitted during the period of the outbreak. Myalgia, conjunctival suffusion, cough with hemoptysis, icterus, and oliguria were significantly more common in patients whose samples were determined positive by MAT. The presence of pulmonary signs and symptoms and renal failure were significantly associated with mortality in patients presumed to be suffering from leptospirosis.     

Celiac disease diagnosis in patients with giardiasis: high value of antitransglutaminase antibodies

OBJECTIVES: The main objective of this study is to assess the presence of celiac disease (CD) in patients with giardiasis and to evaluate the tools for diagnosis of CD in these patients. METHODS: A total of 40 patients with giardiasis were evaluated. Celiac disease was confirmed or discarded by intestinal biopsy and serological markers. Antigliadin antibodies were determined by ELISA and antitransglutaminase antibodies by one-step immunochromatographic assay and ELISA. RESULTS: Out of the 40 patients with giardiasis 37 showed normal intestinal mucosa. In this group, IgA antibodies to gliadin were positive in 7 patients, yielding a specificity of 82%. All of them were negative for transglutaminase antibodies by the immunochromatographic assay and by ELISA (specificity of 100%). The remaining 3 patients showed a subtotal intestinal villous atrophy consistent with CD, however, only two presented IgA antibodies to transglutaminase and gliadin. CONCLUSIONS: Due to its low specificity antigliadin antibodies are not useful for the screening of CD in patients with giardiasis. On the other hand, antitransglutaminase antibodies are highly specific and sensitive. One-step immunochromatographic assay is an easy and economic alternative. The findings of villous atrophy must be supported by other markers of CD to achieve the diagnosis of CD in these patients.     

A reliable screening test for coeliac disease: enzyme-linked immunosorbent assay to detect anti-gliadin antibodies in serum

Abstract A simple, rapid, highly reproducible enzyme-linked immunosorbent assay detecting anti-gliadin antibodies in serum to screen for coeliac disease (CD) is described. By combining the results of anti-gliadin IgA and IgG determinations the overall sensitivity of the assay was found to be 100% and the specificity 96% for children and 99% for adults. Significantly elevated anti-gliadin IgA and IgG antibodies were detected in all 20 children and all 25 adults with untreated CD. False positive results were found in 1/79 histologically normal control and 5/86 disease control children, while for adults false positive rates were 0/74 and 1/34 for the healthy and disease control groups, respectively. Anti-gliadin IgA and IgG was measured in serum samples from 52 coeliac patients (11 children and 41 adults) treated with a gluten-free diet (GFD). Each of the children and 28 of the adults who followed a strict GFD had significantly lower IgA and IgG levels than untreated CD patients. The serum anti-gliadin IgA and IgG levels of the 13 adults not complying with a GFD were similar to those found for untreated CD patients. This assay is recommended as a screening test for CD as well as a tool for follow-up of treated patients.     

IgA anticardiolipin and anti-beta2-glycoprotein I are the most prevalent isotypes in African American patients with systemic lupus erythematosus.

BACKGROUND: Ethnicity plays a role in the prevalence, isotype distribution, and clinical significance of anticardiolipin (aCL) and anti-beta2-glycoprotein I (anti-beta2-GPI) antibodies in patients with systemic lupus erythematosus (SLE). Few studies have been done in the African American population. METHODS: Serum samples from 100 African American patients with SLE were tested for IgG, IgM, and IgA aCL and anti-beta2-GPI antibodies by enzyme-linked immunosorbent assay (ELISA). Computerized clinical data on these patients were reviewed with a specific focus on clinical manifestations of antiphospholipid syndrome (APS). RESULTS: Positivity for at least one isotype of aCL antibodies was found in 33% of the patients, whereas 28% were positive for at least one isotype of anti-beta2-GPI antibodies. IgA was the most prevalent isotype for both antibodies; 24% of the patients in the aCL ELISA and 19% in the anti-beta2-GPI ELISA were positive for IgA. Positivity for both aCL and anti-beta2-GPI in the same patient was seen more frequently with the IgA isotype. Fewer than half of the patients positive for aCL antibodies had medium-to-high levels of antibodies. A few patients had presented thrombotic manifestations, and these patients were positive for aCL (P = 0.01) and anti-beta2-GPI antibodies (P = 0.02). No other manifestations of APS could be significantly correlated with the presence of these antibodies. CONCLUSIONS: Our results show that IgA is the most prevalent isotype among the African American patients with SLE studied. The predominance of the IgA isotype and the low prevalence of medium-to-high levels of aCL antibodies may account for the low frequency of clinical manifestations of APS in these patients.     

Antibodies against Vibrio cholerae lipopolysaccharide, cell-bound haemagglutinin and toxin in the intestinal fluid during convalescence

Specific antibodies to V. cholerae lipopolysaccharide (LPS), cell-bound haemagglutinin (CHA) and toxin (CT) in the intestinal lavages of healthy Thais and Thai cholera patients during the convalescence period were determined by enzyme-linked immunosorbent assay. Only IgM and IgA specific antibodies were detectable in the specimens. All of the persons who were just recovered from cholera had IgA anti-CT and IgA anti-LPS and 82.4% had IgA anti-CHA. The IgA anti-CT, anti-LPS and anti-CHA were detected also in the gut fluids of 70.6%, 94.1% and 88.2%, respectively, of the healthy controls. The mean levels of the IgA antibodies of all specificities between the two groups of individuals were not different. However, the IgM anti-CT and IgM anti-LPS of the cholera patients increased during the convalescence period. The levels, therefore, were significantly higher than those of the controls. The ratios of IgA anti-CT: IgM anti-CT and IgA anti-LPS: IgM anti-LPS among the patients were 2.93:1 and 2.02:1, respectively while those of the controls were 10:1 and 34:1, respectively. IgA antibodies predominated in the lavages of both groups of the individuals.     

Biochemical and ultrasound tests for early diagnosis of active neuro-osteoarthropathy (NOA) of the diabetic foot

To examine humoral and mucosal immune responses to food antigens and their relation to the pathophysiology of type 1 diabetes mellitus, IgA and IgG antibodies to cow's milk antigens (bovine serum albumin (BSA) and beta-lactoglobulin (BLG)) and another food antigen (ovalbumin, (OVA)) in human serum were assessed by enzyme-linked immunosorbent assay (ELISA). If anti-idiotype antibodies to the antibodies were present in serum, they might interfere with the ELISA assay, so suitable microtiter plates were employed to minimize such interference. The levels of IgA and IgG antibodies to the above antigens (P<0.001-P<0.01) and the prevalence of positive sera (P<0.001-P<0.05) in the patient group (n=52, aged 14.5+/-4.1 (S.D.) years) were significantly higher than those in the control group (n=41, aged 13.3+/-6.8 (S.D.) years). Interestingly, the levels of IgA antibodies to all the food antigens examined were elevated in 26 (50%) patients, while the elevation was seen in 3 (7%) healthy controls. The elevation of IgA antibodies in the patients was well correlated with increased concentrations of IgA and transforming growth factor (TGF)-beta, which induces IgA-producing B-cells, in serum. Although the cytokine TGF-beta is secreted from regulatory T-cells (Th3), and is related to oral tolerance, the interleukin-2 (IL-2, Th1)/IL-4 (Th2) ratio in the patient group was significantly elevated (P<0.001), which might indicate that the oral tolerance is impaired in patients. Thus, we demonstrated that both IgA and IgG antibodies to several food antigens are elevated in patients. We suggest that impairment of oral tolerance might be related to the pathogenesis of type 1 diabetes mellitus.