THE RECOMBINANT HUMAN INTERFERON-GAMMA RECEPTOR IS FULLY FUNCTIONAL IN A HUMAN X MURINE HYBRID CONTAINING HUMAN CHROMOSOME-21

It has previously been shown that stimulation of class I MHC antigen expression by human interferon gamma (Hu-IFN-gamma) depends on the presence of both human chromosomes 6 and 21. Even although the presence of human chromosome 6 results in normal expression of the IFN-gamma-receptor on the cell surface, chromosome 21 is required for this biological response. Here, we transfected the cDNA encoding the Hu-IFN-gamma-receptor into a mouse cell line, L(tk-), and into a mouse x human hybrid, GM08, containing the human chromosome 21 as the only human genetic material. Two clones, L-gamma-R.8 and GM08-gamma-R.9, were tested for different biological responses to Hu-IFN-gamma. Only the hybrid containing the human chromosome 21 (GM08-gamma-R.9) exhibited a biological response when assayed for the stimulation of murine class I MHC antigen expression by Hu-IFN-gamma. Moreover, transcriptional induction of 2'-5'-oligoadenylate synthetase and 1-8 genes, as well as antiviral protection, were observed only in the GM08-gamma-R.9 transfectants. These results show that human chromosome 21 encodes a factor which mediates different biological activities of Hu-IFN-gamma.