ANTIBODIES TO BOVINE SERUM-ALBUMIN IN BRAZILIAN CHILDREN AND YOUNG-ADULTS WITH IDDM

OBJECTIVE - To evaluate the prevalence of IgG antibodies to bovine ser um albumin (BSA) in a cohort of Brazilian children and young adults wi th IDDM. RESEARCH DESIGN END METHODS - Sera from 81 subjects with <1 y ear of IDDM (group 1), 111 subjects with >1 year of IDDM (group 2), an d 207 normoglycemic subjects were tested using an immunofluorimetric a ssay. A receiver-operating-characteristic curve was used to establish the threshold of anti-BSA antibody titers defining the positivity of t he assay. RESULTS - The distribution of the fluorimetric index (FI) of anti-BSA antibodies did not have a gaussian profile. Rank sum of FI w as significantly higher inpatients than in control subjects (P < 0.000 1). Average logFI values of both IDDM groups were significantly higher than that of the control group (P < 0.005 for both groups). There was a trend toward higher FI levels in group 1 than in group 2 (P = 0.06) . A FI cutoff of 0.7 optimized the ratio of true-positive to false-pos itive of the assay, with the best equilibrium between sensitivity and specificity. The prevalence of anti-BSA antibodies was 52% in group 1, 47% in group 2, and 28% in the control group (P = 0.0001). An indepen dent association between anti-BSA antibodies and IDDM, with an odds ra tio of 3.03 (P < 0.0001), was observed in a logistic regression analys is. However anti-BSA antibodies explained only 5% of the variability o f IDDM versus NIDDM. CONCLUSIONS - Our results confirm that the preval ence of anti-BSA antibodies is higher in IDDM subjects than in control subjects, even after 1 year of diabetes. However, a large overlap of antibody titers is observed in patients and control subjects, suggesti ng that anti-BSA antibodies are neither sensitive nor specific markers of IDDM.