Catechol-O-methyltransferase activity and aminergic binding sites distribution in human peripheral blood lymphocyte...

We have studied the binding of [3H]dihydroalprenolol, a beta-adrenergic ligand, and [3H]spiroperidol, a dopaminergic ligand, to human peripheral blood lymphocyte subpopulations. The catechol-O-methyltransferase activity on these different cells was also determined. On intact living cells, an unequal distribution of both beta-adrenergic and dopaminergic binding sites was found between B- and T-lymphocyte subpopulations. In each binding, T cells exhibited a lower number of binding sites than B cells. On particulate preparation, catechol-O-methyltransferase activity showed a similar distribution, but binding data with such material were quite different. Although it was not possible to detect dopaminergic binding sites on particulate preparation, T and B lymphocytes contained equivalent numbers of beta-adrenergic binding sites. Different explanations for these results are proposed.