RECEPTORS FOR IGM ON HUMAN-LYMPHOCYTES .2. MITOGEN-INDUCED MODULATION OF RECEPTOR EXPRESSION

  • 1 January 1979
    • journal article
    • research article
    • Vol. 37  (3) , 486-494
Abstract
Human peripheral lymphocytes undergoing blastogenesis induced by phytohemagglutinin (PHA) or concanavalin A did not express receptors for the Fc portion of Ig[immunoglobulin]M (RFc.mu.). Treatment of lymphocytes with PHA produced a dose-dependent loss of RFc.mu. which began 5 h after exposure to the mitogen. Within 24 h after the addition of PHA, the percentage of lymphocytes expressing RFc.mu. had decreased from 65% to 4% and the expression of the receptor for sheep erythrocytes (E) was unchanged. These findings seemed inconsistent with a direct blocking effect of PHA. PHA apparently induced a time-dependent modulation (switch off) of expression of RFc.mu.. Pronase cleavage of surface proteins on cells incubated with PHA for 24 h followed by overnight incubation showed an almost complete irreversibility of RFc.mu. modulation up to 72 h later. Studies using T [thymus-derived] cells isolated by E-rosetting showed that RFc.mu. modulation predominantly occurred on T cells. The modulation of RFc.mu. expression is discussed in terms of its possible role in the immune response.