Deregulated c-fos augments cell proliferation of B cells mediated by lipopolysaccharide.

We have examined effects of the deregulated c-fos protein on the lipopolysaccharide (LPS)-mediated B cell responses using splenic B cells from transgenic lines carrying the mouse c-fos gene under the control of the H-2K (H2-c-fos) and the inducible Mx promoter (Mx-c-fosD). High c-fos expression was induced in Mx-c-fosD B cells by LPS stimulation. DNA synthesis of the B cells from both lines was augmented depending on the amount of exogenous c-fos. This augmentation resulted in the increase of IgM and IgG2b productions in the culture. These results suggest a functional role of c-fos protein in cell cycle progression of the activated B cells.