Kinetic studies of the immunopharmacologic effects of NPT 15392 in mice

NPT 15392 [9-erythro-(2-hydroxy,3-nonyl)-hypoxanthine] was administered in a single intraperitoneal injection to Balb/c mice at a dose of 0.1 mg/kg. Modifications of immune parameters were evaluated 1-14 days after the treatment. NPT 15392 potentiated antibody responses to both T-dependent (SRBC, TNP-KLH) and T-independent (TNP-LPS) antigens and delayed-type hypersensitivity to oxazolone. The proliferative response of spleen cells from NPT-treated mice to stimulation with PHA was depressed, but that to dextran sulphate was augmented. The responses to Con A or LPS were inconsistently modified. NPT 15392 augmented killer cell functions, including both T cell-mediated cytotoxicity against allogeneic tumor cells and NK cell activity against YAC-1 tumor cells. It slightly augmented or depressed ADCC activity against antibody-coated chicken erythrocytes (CRBC) depending on the time of its administration. Concerning the stimulation of NK cell activity, the effect was more marked on spleen effector cells when NPT 15392 was given i.v. and on peritoneal effector cells when it was given i.p. From these results, T helper cells, B cells, and NK cells appeared to be target cells of NPT 15392 action. The various stimulatory effects peaked at different times according to the immune function tested. In addition, the prolonged, sometimes double-peaked action (antibody response to T-dependent antigens, NK activity) indicates complex mechanisms of action which may involve indirect interactions mediated by lymphokines or monokines.