Induction of MHC Class II Antigens on Bovine Cells of Nonlymphoid Origin by Recombinant Bovine Interferon-α and Tumor Necrosis Factor-α

To test a hypothesis that immune mechanisms may be involved in the disease process in cattle persistently infected with and immunotolerant to bovine viral diarrhea virus, the effect of interferon-α_I1 (IFN-α_Il) and -γ (IFN-γ) and tumor necrosis factor (TNF-α) on bovine endothelial, epithelial, and fibroblast cell class II major histocompatibility complex (MHC) gene product expression was investigated. Untreated control cultures did not express MHC class II antigens. However, following exposure to either recombinant bovine IFN-γ or TNF-α (rBoIFN-γ, rBoTNF-α) MHC class II (Ia) antigen expression was induced on these nonlymphoid cell types. rBoIFN-α_Il did not induce class II antigens, but suppressed their induction by rBoIFN-γ and TNF-α. Induction of Ia-antigen expression, which was dependent on de novo protein synthesis, showed dose- and time-dependency, but once induced, Ia-antigen expression appeared to be fairly stable. Bovine viral diarrhea virus, which, at least in vivo, can induce IFN-α, neither induced Ia-antigen expression in the nonlymphoid cell types, nor did the virus interfere with cytokine induction of Ia-antigen expression.