The in vitro effect of phenytoin and carbamazepine on subpopulations of human blood mononuclear cells.

Mononuclear cells from peripheral blood of 10 healthy blood donors were incubated with phenytoin and carbamazepine dissolved in 1% propyleneglycol. Phenytoin 20 mg/1 significantly reduced the percentage of active E rosette-forming T-lymphocytes; to mean 17.6% compared to mean 25.9% in control incubations (P less than 0.05). Carbamazepine 10 mg/1 reduced this percentage to 21.0% (0.05 less than P less than 0.10). Phenytoin reduced the percentage of active T-lymphocytes in 9 of the 10 cell suspensions, while carbamazepine reduced the active T-lymphocytes in 8 of the 10 suspensions. The percentage of total E rosette-forming T-lymphocytes was similarly reduced by 20 mg/1 phenytoin and 10 mg/1 carbamazepine; from 65.3 to 59.5% and to 60.3%, respectively (P less than 0.05, 0.05 less than P less than 0.10). The reduction of active and total T-lymphocytes was concentration-dependent for both drugs. Phenytoin and carbamazepine 5 mg/1 did not influence the percentage of T-lymphocytes. The decrease became apparent at a concentration of 10 mg/1 for both drugs, and grew steadily more marked with increasing drug concentrations up to 80 mg/1. However, the reduction in the percentage of T-lymphocytes was more pronounced for phenytoin than for carbamazepine at all drug concentrations. The percentage of cells with Fc gamma-receptors and of those with receptors for the activated human complement component C3b, were not influenced by phenytoin and carbamazepine, nor were the cells with phagocytizing capacity and the non-phagocytizing cells with membrane-bound immunoglobulin (i.e. B-lymphocytes).