The parallel, time-dependent, bimodal change in lymphocyte cholinergic binding activity and cholinergic influence upon lymphocyte-mediated cytotoxicity after lymphocyte activation.

The potent muscarinic cholinergic antagonist 3-quinuclidinyl benzilate has been used to detect muscarinic acetylcholine receptors on rodent and human lymphocytes. Binding to B lymphocytes was minimal and was not saturable or ligand specific. Half-maximal binding of (3H)-quinuclidinyl benzilate to T lymphocytes occurred at concentrations comparable to those described in other systems, and was displaceable at physiologic concentrations by muscarinic but not nicotinic agonists and antagonists. Binding to T lymphocytes was both saturable and specific, and was found to rapidly increase significantly after mitogen activation. Activation of T lymphocytes or the Lyt 1+ subset produces an early increase and later fall in muscarinic binding, and the ability od cholinergic agonists to augment the effector function of cytotoxic T lymphocytes harvested from alloimmune rat spleen is directly related to the magnitude of muscarinic binding.