title: With(out) a little help from my friends: an IL-12/CD40L-mediated feed-forward loop between CD8+ T cells and DCs.
abstract: CD40-CD40L interactions are important for both antigen-dependent B-cell differentiation and effector and memory T-cell formation. The prevailing view is that CD40L is expressed on activated CD4(+) T cells, which enables them to provide help to high-affinity B cells in GCs and to license DCs for efficient induction of CD8(+) T-cell responses. Interestingly, CD8(+) T cells themselves can also express CD40L and, in this issue of the European Journal of Immunology, Thiel and colleagues [Eur. J. Immunol. 2013. 43: 1511-1517] show that CD40L expression on these cells can be part of a self-sustaining feed-forward loop, in which expression of CD40L is induced by IL-12 and TCR signaling. This provides a paradigm shift in our thinking about the requirements of effector CD8(+) T-cell development and the role herein of CD4(+) T cells to provide help in this process.
authors: Adaptive Immunity Lab, Department of Hematopoiesis, Sanquin Research and Landsteiner Laboratory AMC/UvA, Amsterdam, The Netherlands. m.nolte@sanquin.nl
authors: Martijn A
authors: MA
authors: Nolte
authors: Rene A W
authors: RA
authors: van Lier
mesh_terms: D000818:Animals; D023201:CD40 Ligand / Q000378:metabolism*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D006801:Humans; D018664:Interleukin-12 / Q000276:immunology*; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism*; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology*
chemical_list: D011948:Receptors, Antigen, T-Cell; D023201:CD40 Ligand; D018664:Interleukin-12