CD8+ T Cells Produce the Chemokine CXCL10 in Response to CD27/CD70 Costimulation To Promote Generation of the CD8+ Effector T Cell Pool

摘要

Various cell types can produce the chemokine CXCL10 in response to IFN-γ stimulation. CXCL10 is generally viewed as a proinflammatory chemokine that promotes recruitment of CD8+ and Th1-type CD4+ effector T cells to infected or inflamed nonlymphoid tissues. We show that CXCL10 plays a role during CD8+ T cell priming in the mouse. Genome-wide expression profiling revealed the Cxcl10 gene as a target of CD27/CD70 costimulation in newly activated CD8+ T cells. CD27/CD70 costimulation is known to promote activated T cell survival, but CXCL10 did not affect survival or proliferation of primed CD8+ T cells in vitro. Accordingly, CXCL10 could not fully rescue CD27 deficiency in mice infected with influenza virus. Rather, CXCL10 acted as chemoattractant for other activated CD8+ T cells. It signaled downstream of CD27 in a paracrine fashion to promote generation of the CD8+ effector T cell pool in the Ag-draining lymph nodes. Consistently, CD8+ T cells required expression of the CXCL10 receptor CXCR3 for their clonal expansion in a CD27/CD70-dependent peptide-immunization model. Our findings indicate that CXCL10, produced by primed CD8+ T cells in response to CD27/CD70 costimulation, signals to other primed CD8+ T cells in the lymph node microenvironment to facilitate their participation in the CD8+ effector T cell pool.