The influence of mechlorethamine on the activity of ecto-ATPase of rat lymphocytes.

Mechlorethamine, is an immunomodulator widely used in therapy although its effect on plasma membrane - bound enzymes is unclear. In rats with an inflammatory state, an increased activity of ecto-ATPase was observed both in the B and T subpopulations of lymphocytes. A single administration of mechlorethamine (simultaneously with carrageenin - inflammation factor), either in immunomodulating (5microgram/kg) or cytotoxic (600microgram/kg) dose, decrease the enzymatic activity in both subpopulations but to higher degree in the case of cytotoxic dose. In in vitro studies, after administering mechlorethamine, a diminution of inhibiting potential of the inhibitors blocking the nucleophilic site of proteins was noticed. This confirms the hypothesis that mechlorethamine attacks the catalytic part of the ecto-enzyme containing a nucleophylic group. Classical inhibitors of apyrase - Hg(2+), cerythrosin B and suramine - did not cause any significant change in the activity of ecto-ATPase, what confirms the fact that these enzymes belong to different groups.