Immunomodulatory influence of CD26 dipeptidylpeptidase IV during acute andaccelerated rejection

Background: The intrinsic catalytic dipeptidyl peptidase IV activity of the T cell activation Ag CD26 is crucial for its costimulatory efficacy. Methods:In this study, we investigated the immunomodulatory effect of CD26/ DPP IV,by targeting its catalytic moiety. Results: Treated recipients showed a significant and rapid decrease in TCR, CD3 and CD45 cellular expression kinetics on PBL and a reduction in IL-2 a nd IFN-gamma intragraft mRNA expression. Enzymatic inhibition during sensit ization abrogated accelerated rejection in > 50% of treated recipients. Conclusion: These findings further support the hypothesis that DPP IV/CD26 is associated with allo-Ag mediated immune responses, indicating a graded b ut central involvement in pathways of cellular and humoral immunity.