THE CYTOTOXIC T-LYMPHOCYTE GENE FIBLP WITH HOMOLOGY TO FIBRINOGEN-B AND GAMMA-SUBUNITS IS ALSO INDUCED IN MOUSE MACROPHAGES BY IFN-GAMMA

To identify genes induced in mouse macrophages by IFN-gamma, a cDNA su btraction library of IFN-gamma-induced genes was screened. One of the clones, 36F2, was identified by DNA sequencing as the FIBLP gene. The FIBLP (fibrinogen-like protein) gene is a T-lymphocyte-specific gene t hat is expressed in mouse cytotoxic T lymphocytes but not in helper T lymphocytes or B lymphocytes. The protein sequence shows a high homolo gy to fibrinogen beta and gamma subunits. The FIBLP gene is not expres sed in unstimulated mouse peritoneal macrophages but is induced by IFN -gamma to high levels. FIBLP mRNA is detected by 1 hr after the additi on of IFN-gamma and maximal levels are reached by 12 hr. Expression of FIBLP mRNA was not induced by IL-2, IL-4, IL-10, or TNF-alpha. Though the function of this gene is unknown, its expression in both cytotoxi c T lymphocytes and activated macrophages suggests that FIBLP may play an as yet undefined role in the cytotoxic function of these cells. (C ) 1995 Academic Press, Inc.