TRANSCRIPTIONAL CONTROL OF MHC CLASS II ANTIGEN EXPRESSION ON MOUSE T CELL LINES

We have analysed the factors which regulate MHC class II expression in mouse T cell lines. Two such lines, BW 5147 and PLT‐24.2, were used in this study. Using 5‐azacytidine (5 AzaC) we have shown that hypomethylation of DNA can induce class II antigen synthesis in BW 5147. The expression of class II in PLT‐24.2 cells seems to be under a different control mechanism. Southern blot analysis of I‐Aβ gene in PLT‐24.2 suggests that the expression of class II in this cell line is probably the outcome of a gene rearrangement. We hypothesise that insertion of viral long terminal repeats (LTR) next to the class II genes in transformed T cell lines can act as a promoter for the expression of class II antigens.