The contrasting outcomes of lymphocyte manipulation after solid organ transplantation are allograft rejection and infections, commonly with cytomegalovirus (CMV). Peripheral blood absolute lymphocyte count (ALC) may serve as a predictive marker for these outcomes. Using a retrospective review of clinical and laboratory dataset, we aimed to determine whether a range of ALC (termed “safe ALC corridor”) exists where CMV infection and rejection outcomes are minimal in a cohort of 381 kidney transplant recipients. In an extended Cox model using a time-dependent covariate for peripheral blood ALC, a value below the cut-off of 610 cells/uL was associated with the development of CMV infection both in the overall cohort (Hazard Ratio [HR] 2.25 (95% confidence internal [CI] 1.02-4.96; p=0.043) and the subgroup of high-risk CMV D+/R- mismatch patients (HR 2.91 [95%CI 1.09-7.77]; p=0.033). In contrast, a time-dependent Cox analysis did not show any significant association between ALC and rejection (per IQR decrease, HR 1.2 [95%CI: 0.76-1.9]; p=0.434). Accordingly, a “safe ALC corridor” could not be defined. In conclusion, a low peripheral blood ALC (i.e., threshold of 610 cells/uL) can be used to stratify the risk of CMV disease after kidney transplantation.
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