Regulatory T cells in kidney allograft infiltrates correlate with initial inflammation and graft function.

Background. The relevance of borderline change (BL) and subclinical cellular rejection (SCR) observed in renal transplantation remains to be determined. Several studies have shown in BL and SCR the presence of a Th1 immune response, qualitatively similar to but quantitatively reduced in comparison with infiltrates typical of acute cellular rejection (ACR). Methods. To elucidate the role of regulatory T cells (Tregs) in the local control of the allogenic response, we studied their presence by immunohistochemistry in 24 biopsies with graft dysfunction (12 ACR and 12 BL) and in 16 protocol biopsies at 1 year (eight SCR and eight subclinical BL). Results. The proportion of Tregs in CD4 T infiltrates was higher in BL and SCR when compared with ACR. Moreover, their presence was correlated with the intensity of interstitial inflammation (r0.35, P0.027, n40) and with graft function at the time of the biopsy (r0.37, P0.018, n40). Conclusion. These data suggest Treg recruitment at the acute phase of the allogenic response, where they could act to diminish the interstitial inflammation and its associated lesions.