Effects of serial plasmapheresis on serum IgA levels in IgA‐deficient blood donors with IgA‐suppressor T cells

Seventeen IgA‐deficient blood donors, without antibodies to IgA, underwent plasmapheresis four to eight consecutive times at intervals of 8 weeks or less to provide fresh‐frozen plasma for patients with anti‐IgA. Blood samples, drawn for analysis no more than 1 hour before plasmapheresis and again at the conclusion of each procedure, were analyzed for lymphocyte subpopulations and serum IgA levels. Five lymphocyte subpopulations, including natural killer cells, the suppressor‐inducer CD4 subset, the suppressor‐precursor CD8 subset, non‐major histocompatibility complex (MHC)‐restricted cytotoxic T cells, and CD5+ B cells, were all decreased significantly after plasmapheresis (p<0.05). In a subgroup of IgA‐deficient donors with excessive IgA‐suppressor T‐cell activity, serum IgA increased to levels exceeding 0.05 g per L following the fourth consecutive plasmapheresis procedure. Serum IgA levels did not similarly increase in IgA‐deficient donors without excessive IgA‐suppressor T‐cell activity or in controls without IgA deficiency. Our study shows the potential, in a subpopulation of IgA‐deficient donors who undergo frequent plasmapheresis, for a transient increase in serum IgA to a level no longer considered IgA deficient.