Kinetics of T-lymphocyte subsets and posttransplant opportunistic infections in heart and kidney transplant recipients.

BACKGROUND: The potential use of T-lymphocyte measurements as infection risk markers after solid organ transplant has not been fully investigated. We analyzed the kinetics of T-lymphocyte subsets within the first 8 months posttransplant and their correlation with opportunistic infections (OIs) in solid organ transplant recipients. METHODS: Serial measurement of CD4 and CD8 T cells was performed retrospectively in 48 heart transplant recipients (HTR) and 42 kidney transplant recipients (KTR). Generalized estimating equation models were used to analyze longitudinal data separately for HTR and KTR. RESULTS: An initial CD4 T-cell drop (at months 1 and 2, in HTR and KTR, respectively) coincided with the peak of OIs. HTR with a low nadir CD4 T-cell count (≤ 200/μL) showed poor CD4 T-cell recovery (175 ± 277 cells/μL at baseline vs 242 ± 99 cells/μL at month 8) and their CD8 T cells increased from 153 ± 194 cells/μL at baseline to 601 ± 399 cells/μL at month 8. KTR with a low nadir CD4 T-cell count (≤ 200/μL) showed a modest CD4 T-cell recovery (138 ± 46 cells/μL at baseline vs. 440 ± 448 cells/μL at month 8), and their CD8 T cells increased from 90 ± 41 cells/μL at baseline to 450 ± 242 cells/μL at month 8. HTR developing OIs had lower CD4 (P<0.001) and CD8 T cells (P=0.001) than those without infections, whereas in KTR the risk for OIs seemed restricted to patients with low CD8 T cells. HTR with OIs had a low CD4/CD8 T-cell ratio, whereas KTR had a high CD4/CD8 T-cell ratio. CONCLUSIONS: Determination of T-lymphocyte subsets is a simple and effective parameter to identify patients at risk of developing OIs.