In vitro effects of two immunopotentiators, Isoprinosine and NPT 15392, on murine T-cell differentiation and function.

A new immunopotentiator, NPT 15392, was analyzed in vitro for its capacity to induce a T-cell marker (Thy-1 antigen) and to enhance the mitogen-induced lymphocyte proliferation. The activity was compared with that of Isoprinosine and a putative thymic hormone (thymosin Fr. V). Thymic hormone preparation (thymosin Fr. V) and the non-thymic agents (Isoprinosine and NPT 15392) induced significant percentages (20-30%) of Thy-1 positive cells in nylon wool-nonadherent nu/nu spleen cells. Maximum induction was observed the concentrations of 100 microgram/ml thymosin Fr. V, 1.0 microgram/ml Isoprinosine, and 0.1 microgram/ml NPT 15392. In addition, NPT 15392 or Isoprinosine significantly augmented proliferation of C57BL/6J spleen cells stimulated by the T-cell mitogens (Con A and PHA) and B-cell mitogen (LPS). The effect of both agents was greater on spleen cells from aged mice (18 mth) than on young mice (3 mth). The minimum effective concentration of NPT was lower than that of Isoprinosine. The data indicate that Isoprinosine and NPT 15392 have actions on precursor T cells, mature T cells, and probably B cells.