Differential induction of H-2K versus H-2D class I major histocompatibility antigens by recombinant gamma interferon. Lack of Kk augmentation in a leukemia virus-induced tumor is due to a cis-dominant effect

T-T tumor hybrids were constructed between the AKR SL3 thymoma and an H- 2-distinguishable thymoma cell line. Hybrids were stimulated with IFN- gamma to determine whether the differential augmentation of H-2D vs. H- 2K class I antigen expression by AKR SL3 in response to IFN-gamma was due to effects cis or trans to the noninducible Kk gene. For each of a large number of hybrids tested, the expression of H-2Db, Kb, and Dk, but not Kk, was substantially enhanced by murine rIFN-gamma. These results suggested that the lack of induction of the Kk gene was due to an alteration cis to Kk rather than to the presence or absence of K region-specific, trans-acting negative or positive factors, respectively.