T-lymphocyte subsets in lung transplant recipients: association between nadir CD4 T-cell count and viral infections after transplantation

BACKGROUND: Little is known about the kinetics of T-cell subsets in lung transplant recipients (LTR) and their association with the occurrence of opportunistic infections (OI). OBJECTIVES: To analyze the kinetics of T-lymphocyte subsets in LTR and the association between nadir CD4 T-cell count and viral infections after transplantation. STUDY DESIGN: Serial measurements of peripheral blood CD4 and CD8 T-cell counts obtained during the first year post-transplantation from 83 consecutive LTR and their correlation with both viral OI and community-acquired infections post-transplantation were retrospectively analyzed. RESULTS: LTR with a nadir CD4 T-cell count <200 cells/μl had consistently lower CD4 and CD8 T-cell counts than LTR with a nadir CD4 T-cell count >200 cells/μl (p < 0.001). In LTR with a nadir CD4 T-cell count <200 cells/μl, the cumulative incidence of viral infections detected in peripheral blood and in bronchoalveolar lavage (BAL) samples was higher than in LTR with a nadir CD4 T-cell count >200 cells/μl (p = 0.0012 and p = 0.0058, respectively). A nadir CD4 T-cell count <200 cells/μl within the first three months post-transplantation predicted a higher frequency of viral infectious episodes in BAL samples within the subsequent six month period (p = 0.0066). CONCLUSIONS: Stratification of patients according to nadir CD4 T-cell count may represent a new and simple approach for early identification of patients at risk for subsequent virus infections.