Long-term follow-up of anti-IgA antibodies in healthy IgA-deficient adults.

A follow-up study of anti-IgA antibodies in 159 healthy blood donors with severe deficiency of serum IgA (< 0.05 mg/L) and in 45 donors with decreased serum IgA levels (0.05-799 mg/L), identified in 1971-1980, was carried out. Initially anti-IgA antibodies were determined by a hemagglutination (HA) method and two reexaminations were done in 1990-1992 by an enzyme immunoassay. The median follow-up period was 19 years, during which anti-IgA level was changed considerably in only four persons, increased in two, and high level antibodies (> 1/1000 by HA) appeared in two. In reexaminations anti-IgA antibodies were found in 30 (19%) subjects with severe IgA deficiency and the antibody levels remained relatively constant in those who had high and medium antibody levels. Anti-IgA antibodies were not found in subjects with decreased, but detectable serum IgA. Thus it seems that only those healthy adults who have severe IgA deficiency develop anti-IgA antibodies and their anti-IgA levels remain fairly constant. Of the 159 subjects with severe IgA deficiency, 66 had a history of IgA exposure, but no correlation to anti-IgA development was noted.