title: A trans-acting mechanism represses the expression of the major transplantation antigens in mouse hybrid thymoma cell lines.
abstract: We have fused an H-2- thymoma (BM5R.9) with an H-2+ thymoma (BW5147) and have found that many of the resulting hybrids exhibit an H-2- phenotype. In several hybrids that were analyzed in detail, this phenotype is related to the absence of steady-state H-2 mRNA and shows some instability, possibly related to the loss of chromosomes in segregants. We conclude from our studies that BM5R.9 cells display a trans-acting mechanism that can repress the expression of H-2 antigens, and that the gene(s) causing the repression are not located on chromosome 17. This mechanism is not sufficient to explain the H-2- phenotype of BM5R.9, for which an additional, cis-acting process, must be postulated. We discuss these results in the context of the regulation of expression of the major class I transplantation antigens.
mesh_terms: D000818:Animals; D002459:Cell Fusion; D002460:Cell Line; D005786:Gene Expression Regulation; D006183:H-2 Antigens / Q000032:analysis / Q000235:genetics*; D006822:Hybrid Cells; D051379:Mice; D010641:Phenotype; D013945:Thymoma / Q000235:genetics / Q000276:immunology*; D014158:Transcription, Genetic
chemical_list: D006183:H-2 Antigens