Dominant allele-specific regulation of expression of H-2Kk gene products revealed by somatic cell hybridization.

A study has been made of the H-2 profiles of the AKR thymoma K36 and two series of somatic cell hybrids derived from it. Despite expressing good amounts of the H-2Dk product, the H-2Kk antigen was barely detectable in this tumor, approximately only 1% of that expressed by a comparable AKR lymphoma, 339. The isoelectric focusing profile of the H-2kk product immunoprecipitated from K36 was found to be identical to that from normal AKR lymphocytes. The phenotype of K36 therefore results from regulatory constraints. Fusion of K36 with normal K-2k lymphocytes resulted in hybrids expressing the H-2Kk product. Fusion of K36 with normal H-2b lymphocytes resulted in good expression of the H-2Dk and H-2Db alleles in addition to good expression of the H-2Kb products. The expression of the H-2Kk antigen remained marginal. The data suggest a suppressive mechanism which is trans-acting and dominant and specific for the H-2Kk allele.