Antibodies against bovine albumin and other diabetes markers in French children.

Abstract

Findings in epidemiology and animal experimentation suggest that autoimmunity in insulin-dependent diabetes mellitus (IDDM) may be triggered by dietary cow-milk protein, particularly bovine serum albumin (BSA). Elevated IgG anti-BSA antibodies were found in children from Finland with newly onset diabetes; Finland has the highest incidence of diabetes and cow's milk consumption in the world. We now analyze BSA serology and other diabetes markers in school-age children from France, where diabetes incidence and cow's milk consumption are low. Sera were obtained from three groups: newly diagnosed diabetic (n = 43), islet cell antibody-positive (ICA+) nondiabetic (n = 98), and ICA- healthy control children (n = 267). IgG anti-BSA antibody levels were measured blindly using particle concentration fluoroimmunoassays and analyzed in comparison with ICA titers and human leukocyte antigen-DQB genotypes. There were highly significant differences in BSA antibody levels between all three groups (P < 0.0001). Diabetic patients had elevated anti-BSA levels in 74.4% of cases, compared with 5.5% of control children. In the group of ICA+ non-diabetic children, 20% were anti-BSA-positive. Neither ICA nor BSA antibody titers were significantly related to DQB genotype or sex. ICA titers ( > or = 4 Juvenile Diabetes Foundation units) were present in 84% of diabetic children. Two-thirds of diabetic children were positive for both ICA and anti-BSA antibodies, and none were negative for both markers. Elevated IgG anti-BSA levels are associated with IDDM in the low-incidence French population. In newly diagnosed diabetic children, these antibodies have similar specificity (95 vs. 98%) and slightly lower sensitivity for IDDM than ICA (74.4 vs. 83.7%). Our results may support an immunological role of BSA in diabetic autoimmunity.