Introduction Of The H-2d(K) Gene Into A Class I-Negative Tumor-Cell Line Confers Interferon-Gamma Inducibility Upon The Silent Endogenous H-2k(K) Gene

Kgv cells do not constitutively express class I mRNA or protein. Interferon (IFN)-γ, but not IFN-αβ, induces H-2Dk expression. IFN does not induce H-2Kk expression. We examined constitutive and IFN-inducible class I expression on Kgv cells stably transfected with genomic clones of H-2Kk or H-2Dk and on somatic cell hybrid lines constructed between Kgv cells and constitutively class I-positive cells of a distinguishable H-2 haplotype. Our results suggest that both the lack of constitutive class I expression and the inability of IFN-αβ to induce class I expression on Kgv cells are primarily due to cis-regulatory mechanisms. However, stable introduction of the H-2Dk gene into Kgv cells conferred IFN-γ inducibility upon the silent endogenous H-2Kk gene. Therefore, the failure of IFN-γ to induce H-2Kk expression on Kgv cells is due, at least in part, to a trans-regulatory mechanism.