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

Abstract

We have studied the binding of [ 3H]dihydroalprenolol, a β-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 β-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 β-adrenergic binding sites. Different explanations for these results are proposed.