Molecular analysis of MHC-class-I alterations in human tumor cell lines

Molecular characterization of HLA-class-I expression was investigated in human tumor cell lines at the protein and mRNA levels using locus-specific monoclonal antibodies (MAbs) and probes. Some cell lines exhibited a differential expression of HLA-A and HLA-B products and also showed differences in the inducibility of HLA-class-I genes by gamma-IFN. Thus, gamma-IFN stimulation induced predominantly HLA-B mRNA in the HeP-2 cell line, which showed imbalances in basal levels of HLA-A and HLA-B expression. This unequal inducibility of HLA genes may imply that locus-specific regulatory mechanisms are involved in the expression of individual HLA products. The specific mechanism controlling the differential expression of HLA subsets appears to be independent of c-myc activity. Northern blot analysis found no relationship between c-myc mRNA levels and specific mRNA for HLA-A and HLA-B antigens.