CD127low Expression in CD4+CD25high T Cells as Immune Biomarker of Renal Function in Transplant Patients

Background. Noninvasive tests measuring cellular immunity could help predict immunologic risk and subsequent allograft dysfunction in transplant patients. CD25 is a promising marker of activation. Recent descriptions of CD127 expression as a discriminating factor between regulatory and activated T cells suggest its potential utility. Methods. Expression of CD 127 in CD4+CD25(high) T cells was analyzed by flow cytometry in peripheral blood. from 62 renal transplanted patients and 30 healthy controls. Forty patients presented stable graft function and 22 suffered renal failure. Results. Renal transplant patients showed higher levels of CD127(high) and a lower frequency of CD127(low) than healthy controls (0.63% vs. 0.29% [P<0.001] and 1.4% vs. 2.4% [P<0.001], respectively). However, high frequencies of not only CD127(high) but also CD127(low) showed a significant correlation with serum creatinine levels (P=0.012 and P=0.003, respectively). Allogenic stimulation in vitro increased the frequency of CD127(low) subset in a dose dependent manner. Furthermore, in patients with a high frequency of CD127(low) subset, this consisted mostly of FoxP3 negative cells, discarding their regulatory origin. Median frequency of CD127(low), but not CD127(high), cells showed significant differences between patients with stable function and with renal failure (P<0.005), with 16.7% and 53.1% of individuals above the median CD127(low) value (1.4%), respectively. Conclusion. Quantification of CD127(low) subset through staining of CD4+ T cells with the combined markers CD 127/CD25/CD45RO has been demonstrated to be a significant tool for monitoring the outcome course of renal transplant patients.