A human-mouse hybrid cell line expressing both human leukocyte and histocompatibility-2 antigens

Clone-1d, a sub-line of mouse L cells, was transfected with E. coli neo gene cloned in pSV2 vector (pSV2 neo) to obtain C1-1d neo cells. These cells are able to survive in the presence of geneticin (G418) but are killed by the medium containing hypoxanthine, aminopterin, and thymidine (HAT) because of the deficiency of thymidine kinase (TK) gene. By using these cells, it became possible to produce stable hybrid cells between these neo cells and any other cells since the hybrid cells are selected in the culture medium containing both G418 and HAT. We produced such hybrid cells by fusing C1-1d neo and A431 human epidermoidal carcinoma cells and studied the expression of human leucocyte antigens (HLA) and histocompatibility-2 antigens (H-2) in three hybrid cell lines. We found that one out of three hybrid cell lines expresses both HLA and human beta 2 microglobulin besides H-2 antigens, whereas the other two express only H-2 antigens; this indicated better stability of mouse genes than of human genes.