SIGNIFICANCE OF COWS MILK PROTEIN ANTIBODIES AS RISK FACTOR FOR CHILDHOOD IDDM - INTERACTIONS WITH DIETARY COWS MILK INTAKE AND HLA-DQB1 GENOTYPE

Dietary factors are suspected to play an aetiological role in the deve lopment of insulin-dependent diabetes mellitus (IDDM). We analysed cow 's milk. formula, betalactoglobulin, and bovine serum albumin antibodi es by an enzyme-linked immunoassay in unselected children with nearly diagnosed IDDM and in their non-diabetic siblings and enquired about i nfant feeding practices by questionnaire. Among 410 diabetic sibling p airs matched for age and sex, by logistic regression analysis - includ ing overall duration of breast-feeding, age at introduction of dairy p roducts, recent consumption of cow's milk and HLA-DQB1 genotype (''hig h/moderate'' vs ''low/decreased'' risk of IDDM)-bovine serum albumin I gG antibody levels (OR 2.12, 95 %CI 1.25-3.57) and genetic risk (OR 3. 81, 95 %CI 2.43-5.17) were positively associated with IDDM: cow's milk formula IgM antibodies were inversely associated with the risk of IDD M (OR 0.50, 95 %CI 0.29-0.87). Of the diabetic sibling pairs, 42 were identical for HLA-DQB1 alleles associated with IDDM risk or protection (DQB10201, *0301, *0302 and *0602/03). In these 42 pairs, children w ith IDDM had higher median levels of bovine serum albumin IgG, of beta lactoglobulin IG, and of cow's milk formula IgG and IgA antibodies tha n the non-diabetic siblings (p < 0.05). In conclusion, children with I DDM have higher levels of cow's milk protein antibodies than their HLA -DQB1-matched sibling controls, and these high levels of antibodies ar e independent risk markers for IDDM.