Active alpha2 and beta adrenoceptors in lymphocytes from patients with chronic lymphocytic leukemia

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Abstract
A single population of alpha2 adrenoceptors was characterized in intact B lymphocytes from patients with chronic lymphocytic leukemia (B‐CLL) by binding and saturation studies with 3H labelled yohimbine and by competition studies with alpha adrenergic antagonists. While the affinity of B‐CLL alpha2 adrenoceptors was low (KD: 9.81 nm‐20.98 nm), each cell expressed a large number of receptors. No binding of the alpha1 adrenoceptor antagonist prazosin was observed and the binding properties of beta adrenergic receptors (assayed with 3H‐labelled dihydroalprenolol), were similar to those described for normal lymphocytes. Reaction of B‐CLL with the beta adrenergic agonist isoproterenol raised the levels of cAMP in 11/13 patients tested, and in 8 of these, incubation with the alpha2 adrenergic agonist clonidine prevented the effect and reduced the basal cAMP levels. The presence of active alpha2 adrenoceptors on B‐CLL lymphocytes may be involved in the regulation of metabolic pathways that affect cell functions and favor neoplastic growth.