CD 154 Blockade Alters Innate Immune Cell Recruitment and Programs Alloreactive CD 8 + T Cells into KLRG-1 high Short-Lived Effector T Cells

CD154/CD40 blockade combined with donor specific transfusion remains one of the most effective therapies in prolonging allograft survival. Despite this, the mechanisms by which these pathways synergize to prevent rejection are not completely understood. Utilizing a BALB/c (H2-K) to B6 (H2-K) fully allogeneic skin transplant model system, we performed a detailed longitudinal analysis of the kinetics and magnitude of CD8 T cell expansion and differentiation in the presence of CD154/ CD40 pathway blockade. Results demonstrated that treatment with anti-CD154 vs. DST had distinct and opposing effects on activated CD44 CD62L CD8 T cells in skin graft recipients. Specifically, CD154 blockade delayed alloreactive CD8 T cell responses, while DST accelerated them. DST inhibited the differentiation of alloreactive CD8 T cells into multi-cytokine producing effectors, while CD40/CD154 blockade led to the diminution of the KLRG-1 long-lived memory precursor population compared with either untreated or DST treated animals. Moreover, only CD154 blockade effectively inhibited CXCL1 expression and neutrophil recruitment into the graft. When combined, anti-CD154 and DST acted synergistically to profoundly diminish the absolute number of IFN-c producing alloreactive CD8 T cells, and intra-graft expression of inflammatory chemokines. These findings demonstrate that the previously described ability of anti-CD154 and DST to result in alloreactive T cell deletion involves both delayed kinetics of T cell expansion and differentiation and inhibited development of KLRG-1 memory precursor cells. Citation: Ferrer IR, Wagener ME, Song M, Ford ML (2012) CD154 Blockade Alters Innate Immune Cell Recruitment and Programs Alloreactive CD8 T Cells into KLRG-1 Short-Lived Effector T Cells. PLoS ONE 7(7): e40559. doi:10.1371/journal.pone.0040559 Editor: Mehrdad Matloubian, University of California, San Francisco, United States of America Received March 16, 2012; Accepted June 8, 2012; Published July 5, 2012 Copyright: 2012 Ferrer et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: This work was supported by National Institutes of Health grants AI073707 and AI079409 to Mandy L. Ford. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. * E-mail: mandy.ford@emory.edu