Study of activated T cells in man. I. Discrepancy between Tac antigen and DR Antigen on T cells in patients with primary immunodeficiency.

DR and Tac antigens are present on T cells activated in vitro with mitogens and antigens but lacking on resting T cells. Freshly prepared peripheral blood T cells from patients with common variable immunodeficiency ( CVI ) and isolated IgA deficiency ( IAD ) were examined for the presence of DR and Tac antigens, using monoclonal antibodies and a fluorescence-activated cell sorter. Both Tac+ and DR+ T cells were significantly (P less than 0.05) increased in the patient group when compared with age- and sex-matched controls; however, a discrepancy was observed in the proportions of Tac+ T cells and DR+ T cells. This study demonstrates that, in certain patients with CVI and IAD , T cells are activated in vivo, and Tac and DR antigens could be expressed during different stages of T-cell activation.