INDUCTION OF MURINE CD5 EXPRESSION BY V-H-RAS

The murine CD5 surface antigen is a frequent marker on B-lineage cell lines produced from bone marrow infected with retroviruses expressing v-H-ras. Since CD5(+) B cells cannot be detected in adult murine bone marrow either the viral targets of transformation are a minor contamin ating population of CD5(+) B-lineage cells or thr v-H-ras oncogene is inducing the expression of CD5 on B-lineage cells not previously expre ssing this marker. We have found that v-H-ras can induce the expressio n of CD5 on two CD5(-) pre-B-cell lines established from murine bone m arrow. This induction correlates with increased steady-state levels of CD5 mRNA. These results present the possibility that CD5 expansion ma y be modulated by specific signalling as well as early lineage commitm ent.