Cellular aspects of selective IgA deficiency.

Five patients with no detectable serum IgA (less than 20 mug/ml) and one patient with low serum IgA were compared to normal subjects. The number of circulating E-RFC was normal as was the lymphocyte DNA synthesis induced by PHA, Con A, and streptokinase-streptodornase. The patients had normal numbers of IgA-bearing lymphocytes and normal or increased numbers of B cells. Purified anti-immunoglobulin antibodies specific for IgG, IgA and IgM induced a normal lymphocyte DNA synthesis as did PWM. The patients' lymphocytes were able in vitro to transform into actively secreting IgA plasmocytes. This transformation was determined by counting the IgA and immunoglobulin-containing cells and then measuring the IgA and IgG secretion in the cultures. In some patients PWM was selectively suppressive in IgA B-cell transformation into IgA secreting cells; in the other patients PWM had no effect on the IgA B-cell differentiation. PWM enhanced the IgG secretion in the patients' cultures as well as IgA and IgG secretion in the normal controls.