Selective IgA deficiency in juvenile-onset insulin-dependent diabetes mellitus.

Variation of serum immunoglobulin (Ig) levels and increased frequency of selective IgA deficiency are frequently associated with autoimmune diseases. In insulin-dependent diabetes mellitus (I.D.D.M.) pathogenesis autoimmunity is known to play a causative role. Aim of the present study was to evaluate serum major immunoglobulin subclasses levels and frequency of IgA selective deficiency in juvenile onset I.D.D.M. IgG, IgA, IgM concentrations were determined in 191 insulin-dependent children and adolescents (100 males, 91 females; mean age 10.6 divided by 4.8 yrs; mean duration of I.D.D.M. 5.7 divided by 3.9 yrs) and in 180 age-matched healthy controls. Mean Ig levels were comparable among both group. Duration of I.D.D.M. did not affect mean serum Ig levels. Selective IgA deficiency was found in 7 on 191 diabetics: this gives a prevalence of the defect of 1:27, which is higher than in the Italian pediatric population (1:500). HLA typing evidenced 2 DR3 positive patients, 2 DR4, 1 B8-DR3 and 1 B8-DR3/DR4. The significance of selective IgA deficiency in I.D.D.M. is discussed.