CHARACTERIZATION OF THE RECEPTOR FOR IGM PRESENT ON HUMAN LYMPHOCYTES-B

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  • 1 January 1979
    • journal article
    • research article
    • Vol. 36  (3) , 569-577
Abstract
The presence of a receptor for the Fc of Ig[immunoglobulin]M (.mu.FcR) was demonstrated on the pathological B [bone marrow-derived] cells of all 16 patients with hairy-cell leukemia and most, but not all, of 24 cases of chronic lymphocytic leukemia, by a rosette method employing ox erythrocytes sensitized with purified IgM (EAM). This .mu.FcR was demonstrated on a small population of normal human mononuclear cells from peripheral blood. Pathological B cells with this receptor (BM) simultaneously expressed a different and distinct receptor for the Fc of IgG, and were detectable without preincubation in medium containing fetal calf serum (FCS). The .mu.FcR on B cells was blocked by Fcs.mu. and IgM, but not by F(ab'')2.mu. fragments or by IgG, whether monomeric or aggregated. Monomeric IgM and IgM bound to its antigen blocked much more effectively than pentameric IgM. B cells also possessed surface Ig and the Ia-like P29,34 antigen and an antiserum to this antigen blocked the .mu.FcR. The .mu.FcR On B cells differs in a number of ways from the .mu.FcR reported on T [thymus-derived] cells and these differential characteristics were discussed in detail. The .mu.FcR was rapidly shed and resynthesized when washed BM cell were maintained in medium not containing FCS and the general importance of this phenomenon in any study of .mu.FcR was considered. BM cells are apparently memory cells and the .mu.FcR may plays a part in the immune response.