DISTRIBUTION OF A RECEPTOR FOR IGM (MU-FCR) ON HEMIC CELLS

A range of normal and malignant haemic cells is examined for expression of receptors of the Fc of IgM (μFcR) in order to establish the distribution and possible nosological significance of this receptor. It is shown that μFcR expression by freshly isolated cells is restricted to a small population of normal lymphocytes and to the pathological B cells of most of 45 cases of chronic lymphocytic leukaemia (CLL) and all 23 cases of hairy‐cell leukaemia (HCL) examined. The pathological cells of acute lymphoblastic leukaemia (eight cases), prolymphocytic leukaemia (two cases), a variety of non‐Hodgkin lymphomata (eight cases) and immunoproliferative disorders (25 cases), Hodgkin disease (three cases), and a range of myeloid and histiocytic proliferations (22 cases) were all negative for the μFcR. The pathological cells of the Sezary syndrome were also shown to possess a μFcR, but this required a period of in vitro incubation in RPMI medium containing foetal calf serum for its demonstration. This and other differences between μFcR expression by T‐ and B‐cells are discussed. The possible immunological, nosological, and diagnostic significance of the observed restriction of μFcR expression is considered. Copyright © 1979 Wiley‐Liss, Inc., A Wiley Company