Differences in β‐adrenergic receptor density and adenylate cyclase activity between normal and leukaemic leukocytes

Abstract

An identical class of high-affinity binding sites for the 125I-labeled .beta.-adrenergic antagonist hydroxybenzylpindolol, was identified on intact human normal and leukemic peripheral blood leukocytes. On normal unfractionated lymphocytes, polymorphonuclear leukocytes and monocytes, receptor density did not differ significantly (1200-1400 receptors/cell; P > 0.3), but it was higher on B- han on T-lymphocytes (P < 0.05). In leukemia, monocytic blast cells expressed highest receptor numbers; very low receptor density was seen on the pathologic B-cells from chronic lymphocytic leukemia. Among normal leukocytes, adenylate cyclase activation by hormones (isoproterenol, prostaglandin E1, histamine) and NF was strongest in plasma membranes from monocytes, but very weak in polymorphonuclear leukocytes, either due to uncoupling of hormone receptors from adenylate cyclase or to low catalytic activity. In T-cells, enzyme activity was significantly lower than in B-cells. Loss of adenylate cyclase sensitivity to hormones and F- occurred in leukemic cells from chronic and acute lumphocytic leukemia.