DOWN-REGULATION OF BETA-ADRENERGIC RECEPTORS INDUCED BY MITOGEN ACTIVATION OF INTRACELLULAR SIGNALING EVENTS IN LYMPHOCYTES

The expression of beta-adrenergic receptors on murine lymphocytes stim ulated with concanavalin A was studied. A decrease in beta-adrenocepto r number on T lymphocytes and a diminished response to specific agonis t stimulation at the peak of proliferation was found. The blockade of cell proliferation by tyrosine kinases or protein kinase C inhibitors reversed the decrease in beta-adrenoceptor number. PMA plus ionophore or interleukin-2 but not PMA alone were able to induce beta-adrenocept or down-regulation accompanying cellular proliferation, These results showed that the intracellular signals triggered during lymphocyte acti vation are involved in beta-adrenoceptor down-regulation and it would represent the loss of a mechanism that exerts negative neuroimmune con trol of cellular proliferation.