B‐CLL cells express true endogenous E receptor after culture with T‐cells and mitogens

Culture studies of peripheral blood mononuclear cells from seven typical cases of B-cell chronic lymphatic leukaemia (CLL) showed that, in the presence of PHA or Con A and greater than or equal to 20% autologous or allogeneic T-cells, CLL cells express true sheep erythrocyte (E) receptor after 2-5 d, but fail to stain with a panel of anti-T-cell sera. In contrast to similarly cultured hairy cells (HCs), the cultured CLL cells continue to express light-chain-restricted surface immunoglobulin (SIg) and show no change in their morphology. The continued SIg positivity and staining with a panel of monoclonal antibodies indicated that the high proportion of E+ cells could not be attributed to the outgrowth of normal T-cells or to mitogen-induced non-specific stickiness. Repeated addition of supernatants from cultured T-cells caused no phenotypic changes and therefore excluded the possibility of shedding and passive acquisition of E receptor. The points of similarity and difference between the responses of CLL cells and HCs cultured in a like manner are briefly considered in relation to the possible lineages of these two cell types.