Humoral immunity against viral antigens in insulin-dependent diabetes mellitus (IDDM): altered IgA class immune response against mumps virus.

Two hundred and ten pediatric IDDM patients with long duration of illness and their matched controls (age range 2-19 years) were analysed for mumps antibodies in IgG, IgM and IgA antibody classes by enzyme linked immunosorbent assay (ELISA). About 70% of both patients and controls had antibodies against mumps virus. However, IDDM patients had higher mean levels of IgA class antibodies than the controls, while no difference was found in IgG or IgM class antibodies. The elevated IgA class mumps antibodies did not correlate with elevated levels of IgA class Coxsackie B4 or cytomegalovirus antibodies. This elevation of IgA antibody levels was evident already early after mumps infection and seemed to persist several years, since the difference was most pronounced in the oldest age group. Female patients as well as female controls had significantly higher IgG and IgM antibody levels compared to males. This may at least in part be explained by a difference in the age distribution in females compared to males and may suggest different age-dependent epidemiology of mumps between boys and girls in this material. No such difference was found in IgA levels between the sexes.