The selective IgA deficiency is the most common immunoglobulin deficiency of man, occurring in roughly 1 in 500-3000 individuals (3, 7). There is a high incidence of rheumatoid arthritis (RA), systemic lupus erythematosus (SLE) and a number of other auto-immune diseases, among IgA-defi-cient individuals (1, 7V In RA and SLE not associated with IgA deficit ncy, levels of IgA are usually elevated (2). D-penicillamine, a drug often used to control disease activity in RA, has been reported to depress IgA, IgM and IgG levels and sometimes to induce an IgA deficiency (4, 5).