Low Absolute Lymphocyte Count Associated With Anti-Thymocyte Globulin Induction May Be a Predictor of Early...

Cytomegalovirus (CMV) can cause serious morbidity in transplant patients. Lymphocyte depletion by anti-thymocyte globulin (ATG) may persist for 6 months post-induction, and lower absolute lymphocyte counts (ALC) may increase the risk for CMV. We sought to find the relationship between ALC at induction and CMV viremia in the first 6 months post-transplant.

An analysis of transplant recipients within a set period of time with uniformed induction therapy and CMV prophylaxis. ATG was a primary component of induction and ganciclovir or valganciclovir as prevention of CMV infection. The cohort was dichotomized into low ALC (≤ 0.3 × 10⁹ cells/L) and high ALC (> 0.3 × 10⁹ cells/L) based on lowest ALC during the first 14 days and their clinical characteristics analyzed. CMV viremia was defined as PCR value of > 137 IU/mL regardless of symptoms.

A total of 44 patients were included in this study. CMV viremia occurred in 18% (n = 8). Patients were more likely to develop CMV if post-induction ALC was ≤ 0.3 × 10⁹ cells/L (28% vs. 0%, p = 0.029) and remained significant when adjusted for CMV serostatus (p = 0.04). The total ATG dose (7.5 vs. 4.5 mg/kg) was not predictive of CMV (37% vs. 17%, p = 0.3) nor was treatment for rejection (25% vs. 14%, p = 0.5. Rejection occurred in 7% compared to 20% of patients in the low vs. high ALC group (p = 0.4).

In pediatric heart transplant recipients, there is a higher incidence of CMV if ALC ≤ 0.3 × 10⁹ cells/L during induction, regardless of serostatus. Low ALC levels during induction may identify a high-risk group that could benefit from an altered CMV prophylactic regimen.