Induction of survival and proliferation of transitional, naïve, IgM memory, and switch memory subsets with/out stimulation. Up-regulation of CD38 and IGM but naïve B cells do not increase IgA and IgG. Cell-contact-dependent effect. Enhancement of survival of SLE patient B cell subsets, increase CD38 expression and IgM and IgG secretion. The gene discussed is CD40LG; the disease is systemic lupus erythematosus.