Effect of transforming growth factor- beta sub(1) on microglial MHC-class II expression

In the present report, the effects of IFN- gamma and transforming growth factor beta sub(1) (TGF- beta sub(1)) on major histocompatibility complex class II (MHC-II) gene expression in isolated mouse brain microglial cells, in the MH-S macrophage cell line and in the primary mouse macrophage cultures were examined. IFN- gamma is a potent inducer of MHC-II gene and this induction was further elevated in microglia by TGF- beta sub(1), while TGF- beta sub(1) inhibited IFN- gamma induction in macrophages. The enhancing effect of TGF- beta sub(1) was also detected in microglia at the protein level. Transient transfection of microglia with 5' deletional mutants of the MHC-II IA sub( alpha ) promoter linked to the chloramphenicol acetyltransferase reporter gene demonstrated that TGF- beta sub(1) acts at the transcriptional level to enhance the MHC-II expression induced by IFN- gamma .