ALTERED CD40 LIGAND INDUCTION IN TOLERANT T-LYMPHOCYTES

CD40 ligand (CD40L) is a member of the tumor necrosis factor superfami ly and is expressed on the surface of activated T lymphocytes. The int eraction of CD40L with CD40 on B cells results in B cell activation, i mmunoglobulin (Ig) secretion and Ig class switching. To study anergy a s a mechanism of murine CD4 T cell tolerance, we determined both in vi vo and in vitro that CD3-activated anergic cells are deficient in the ability to stimulate B cell proliferation, and that anergic cells are defective for the T cell receptor/CD3-mediated induction of CD40L expr ession. These results have implications for the recruitment of B cell responses by anergic T cells in vivo.