Mouse Recombinant Interferon-β Augments the Induction of Macrophage Cytolytic Activity by Interleukin-2 In Vitro

Abstract

We investigated the augmenting effect of mouse recombinant interferon-β (MurIFN-β) on the induction of macrophage (Mϕ) cytolytic activity by interleukin-2 (IL-2). C3H/He spleen cells were cultured with various doses of recombinant (r) IL-2 and/or MurIFN-β for 4 days, and their cytotoxic activities against syngeneic Mϕ were assessed by a 4-h ⁵¹Cr-release assay. Although MurIFN-β itself induced little Mϕ cytolytic activity, it significantly augmented the IL-2-induced cytotoxicity against Mϕ. MurIFN-β showed a dose-dependent enhancement on the induction of anti-Mϕ activity by IL-2 with a peak at 2,000–10,000 U/ml, and the augmenting effect of rIFN-β was more marked on lower doses of rIL-2 than on higher doses. This augmenting effect was also observed in IFN-α, whereas IFN-γ showed no influence on IL-2-induced anti-Mϕ activity. The phenotype analysis by depletion technique with antibody and completement showed that anti-Mϕ effectors induced by either rIL-2 or the combination of rIL-2 and rIFN-β were Thy-1⁺, asialoGM1⁺, L3T4⁻, and Ly2⁻. These results suggest that IFN-α or IFN-β has a synergistic effect with IL-2 on the induction of nonspecific killer cells with Mϕ cytolytic activity.