Effects of Interferon on the Lymphocyte Subset in the Blood and Lymphoid Organs in Mice

ABSTRACT The effects of mouse interferon-α/β (MuIFN) or poly(I):poly(C) injection on the lymphocytes in the blood, thymus, and spleen of C3H/HeN mice were examined. A single injection of MuIFN (2 × 106 to 2 × 107 IU/kg of MuIFN) or poly(I):poly(C) (0.12-1.2 mg/kg) caused (i) a significant lymphocytopenia without any evidence of direct cytotoxic effects on lymphocytes in the blood or lymphoid organs, (ii) a significant decrease in the number of T cells both in the thymus and spleen along with a significant increase in the number of non-T cells in the splenic white pulp, and (iii) a differential decrease in the number of blood T-cell subsets ("suppressor/cytoxic" subset was decreased continuously whereas "helper" subset only transiently). The differential effect on T-cell subsets could explain the complicated effects of IFN on the cell-mediated immune response.