Muscarinic cholinergic receptors on circulating human lymphocytes: evidence for a particulate binding site.

Lymphocytes from thirteen normal volunteers were investigated for their muscarinic cholinergic receptors content. A particular binding site was characterized with 3H-quinuclidinyl benzilate; saturation binding occurred at 80 X 10(-9)M and scatchard analysis provided a dissociation constant of 40 X 10(-9)M. These results showed that there were about 4000 muscarinic receptors on human lymphocyte. Although, it is possible to demonstrate the presence of binding site on a particulate preparation, the significance of such low-affinity receptor is yet unclear.