Expression and regulation of Q8 b in a transfected cell line

RNase protection experiments showed that Q8 ^b was actively transcribed in a stably transfected cell line. Moreover, Q8 ^b responded to interferon- (IFN-) treatment with increased levels of mRNA expression. Thus Q8 ^b demonstrates a regulatory response to IFN- characteristic of many other class I genes. Cell surface expression of a Q8^b product could also be detected by flow cytometric analysis with the Qa-2-specific monoclonal antibody D3.262. The expression of the Q8^b cell surface product increased only slightly after cells were treated with IFN-. The Q8^b cell surface product was not sensitive to cleavage by phosphatidylinositol-phospholipase C. These results suggest that the Q8^b product, unlike the predominant forms of Qa-2-bearing molecules, is not anchored via phosphatidylinositol to the cell membrane. These results also suggest that Q8 ^b has the potential to contribute to the Qa-2 phenotype in vivo. Address correspondence and offprint requests to: L. Flaherty.