Ecto-ATPase from rat lymphocytes--in vivo studies on the influence of levamisole

Levamisole, known for a long time as an antiparasitic drug due to its immunomodulating properties, has been used in the therapy of immune disorders. The action of levamisole depends on the dose and the manner of administration, and it seems interesting to establish whether similar dependencies exist for the membrane enzymes of lymphocytes. Ecto-ATPase, the enzyme tightly integrated with cytoplasmic membrane, was chosen to examine these effects. The in vivo studies were conducted on rats with carragenine-induced inflammation. Levamisole was administered at two doses: high (2.5 mg/kg) and low (0.25 mg/kg), according to two schedules: a) at a single dose, simultaneously with carragenine, 24 h before or 24 h after induction of inflammation; the lymphocytes were collected five times every 24 h, and the activity of ecto-ATPase was determined; b) at four doses, every 24 h after carragenine injection; the lymphocytes were collected 120 h after the induction of inflammation. The results of our studies indicate that levamisole reduces the activity of ecto-ATPase in both populations of lymphocytes in vivo. An apparent deactivation of ecto-ATPase of lymphocytes T was observed when high doses of levamisole were administered four times. In the case of a single low dose of levamisole, the deactivating potential of this compound was not so evident, both for lymphocytes B and T. Different reactions of the enzyme from lymphocytes T and B to the levamisole observed in in vivo studies and different effects of inhibitors in vitro, suggest the dissimilarity of the structure of ecto-ATPases from both populations of lymphocytes.