Tregs have gained importance in transplantation due to the findings of their ability to efficiently control alloimmune responses. The findings in LTR however are contradictory. Several studies have correlated low Treg levels in bronchoalveolar lavage with development of AR and BOS. Another study found no correlation between frequency of Tregs and BOS outcome, although a role of CCR7+CD45RA- Tregs in protection against development of BOS was observed. In the current study lung transplant recipients showed little change in Tregs in peripheral blood over the first year of transplantation and there was no change in those with AR. Our results confirm the lack of association of peripheral blood Treg levels with AR and lung pathology shown by others. Although an association between immunosuppressant regimen and Tregs has been demonstrated in other solid organ transplants, in our cohort no correlation with TAC levels and Tregs was observed at any time point. AbMole Octinoxate Despite TCM cells seem to 
be more resistant to depletion after induction therapy with Campath-1H, the impact of several immunosuppressants in memory T cells remain to be fully elucidated. In a different retrospective study of living donor renal recipients after alemtuzumab induction AR inferred an increased proportion of CD4+ TEM and CD8+ TEMRA 3 years post-Tx. No prospective data on lung transplant patients and memory subsets have been performed. In the present study all the LTR were under the same immunosuppressive regimen without induction therapy, thus the potential impact of induction immunosuppression on memory T cells is avoided. Within effector subsets, Th17 cells may be involved in allograft rejection in animal models and IL-17 has been associated to the development of BOS in LTR. In our cohort no correlation of Th17 cells, measured by either intracellular or supernatant secretion of IL-17, with AR was observed. Furthermore, different ratios of effector subsets versus Tregs or na?ve T cells in blood were assessed but none of them achieved statistical significance. Our data point to an increased number of CD8+ TEM before Tx in patients who later developed an AR episode. The differences were still significant after 2 months post-Tx. This observation was not accompanied with increased production of interferon-gamma or IL-17 after polyclonal stimulation in LTR with AR. More importantly, the patients with end-stage lung disease with CD8+ TEM cells higher than 185 cells/mm3 AbMole BI-9564 presented a substantial increased risk of suffering AR episode. The present study is the first showing a direct association of high levels of pre-Tx TEM cells and AR risk in LTR. There are few attempts in solid organ transplantation to point out memory T subsets as inducers of AR.