Inhibition of lymphocyte capping and transformation by propranolol and related compounds.

1 The effects of propranolol on phytohaemagglutinin (PHA)-induced transformation of murine T lymphocytes and capping of anti-IgG on the surface of murine B lymphocytes have been examined. 2 A 50% inhibition of transformation was observed with 10(-5) M propranolol, whereas a higher concentration, of the order of 10(-3) M propranolol was required to inhibit capping by 50%. The (+)-and (-)-isomers of propranolol proved equipotent in these respects, and the relative potencies of selected analogues of propranolol (alprenolol, oxprenolol, metoprolol, practolol, and sotalol) coincided with their potencies as membrane stabilizers; however, lymphocyte transformation was consistently more sensitive than capping. 3 Similar effects were also seen with quinidine, chlorpromazine and lignocaine, and it was concluded that the inhibition of both lymphocyte functions was due to the membrane stabilizing actions of propranolol.