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Costimulation through the inducible costimulator ligand is essential for both T helper and B cell functions in T
Tak W Mak1, Arda Shahinian, Steve K Yoshinaga
1Advanced Medical Discovery Institute, and Ontario Cancer Institute, Department of Medical Biophysics , University of Toronto, Toronto, Ontario M5G 2C1, Canada. tmak@uhnres.utoronto.ca
Abstract:
Costimulation through the inducible costimulator (ICOS) and its ligand (ICOSL) is essential for T cell-dependent B cell responses, but the cellular and temporal dynamics underlying its in vivo effects are poorly defined. Here we have shown that Icosl(-/-) and Icos(-/-) mice had similar phenotypes and that ICOS-ICOSL costimulation modulated the early but not late phases of IgG1 affinity maturation. Exploiting the adoptive transfer of T or B cells from primed Icosl(-/-) mice, we provided genetic evidence that costimulation through ICOSL was essential for primary but not secondary helper T cell responses and for the control of both T and B cell activities, resulting in T cell-dependent IgG1 production.