Serum IgA deficiency and anti-IgA antibodies in pernicious anemia

Three pernicious anemia (PA) patients with selective IgA deficiency and anti-IgA antibodies in their sera were followed for over 3 years. After instituting therapy with cyanocobalamin there was a slight increase in the anti-IgA antibodies. After 1 year the titers of anti-IgA antibodies in the sera of these patients declined significantly as compared to the values before treatment (P less than 0.02), and after 2 years one patient had no measurable anti-IgA antibodies, yet no IgA appeared in the serum of any of the three. Further, in a medium with no anti-IgA the lymphocytes of these patients were not capable of producing IgA in vitro. Thus, the reason for the IgA deficiency in PA appears to be linked to the function of B cells rather than to anti-IgA antibodies.