Imbalances in T cell subpopulations associated with immunodeficiency and autoimmune syndromes

Abnormal proportions of the distinct T cell subpopulations binding the Fc portion of IgM (T·M) cells and those bearing receptors for the Fc portion of IgG (T·M) cells, were observed in blood samples from patients who had congenital or acquired abnormalities of the thymus, severe combined immunodeficiency, or an unexplained primary deficiency in cell‐mediated immunity; most had too few circulating T·M cells and often an overabundance of T·G cells. In an in vitro evaluation of lymphocytes from one of three thymoma patients with an elevated T·G subpopulation, removal of T·G cells abrogated the suppression of T·M cell help of B cell differentiation induced by pokeweed mitogen. A spectrum of patients with sex‐linked infantile agammaglobulinemia, variable hypogammaglobulinemia, and selective IgA deficiency, and a few patients with autoimmune syndromes infrequently had distorted representation of these T cell subpopulations in the circulation. This suggests that B cell dysfunction in many of these patients is not merely due t o numerical excesses or insufficiencies of helper or suppressor T cells.