The HLA proteins and a related protein of 28 kDa are preferentially induced by interferon‐γ in human WISH cells

The HLA-A,B,C proteins are preferentially induced by interferon (IFN)-gamma. An increase in their synthesis and of their expression on the cell surface can be observed at concentrations of IFN-gamma which are lower than those inducing an antiviral effect. On the other hand, with IFN-alpha and beta, induction of these proteins can be observed only in the antiviral range of IFN concentrations. In human WISH cells, IFN also induces a protein with a molecular mass of 28 kDa (28K). The efficiency of IFN-beta and gamma in inducing this protein is correlated to the efficiency with which they induce the HLA-A,B,C proteins. The 28K protein can be immunoprecipitated with antibodies against beta 2-microglobulin, just as the HLA proteins; yet it can be clearly distinguished from the HLA proteins in several respects: (a) it is not a cell surface protein but rather an intracellular one, with a relatively short half-life, (b) partial peptide mapping suggests that it contains sequences distinct from those of which the HLA alpha chains or beta 2-microglobulin are comprised and (c) the extent of its induction by IFN is much larger than that observed for the HLA proteins.