Date: Saturday, May 30, 2020
Session Time: 3:15pm-4:00pm
Presentation Time: 3:30pm-4:00pm
*Purpose: Iatrogenic suppression of T cells is intended to prevent rejection after solid organ transplantation (SOT). This is complicated by opportunistic infections, most notably cytomegalovirus (CMV). Studies have suggested a low absolute lymphocyte count (ALC) as a predictor for CMV infection. Allograft rejection has also been suggested to correlate with absolute regulatory T-cell counts, but whether a threshold of ALC can be defined to assess risk of rejection has not been defined. We aimed to determine the optimal ALC range (termed “safety corridor”) associated with low risk of CMV infection and rejection outcomes after SOT.
*Methods: Laboratory and clinical data were collected from kidney recipients transplanted between 01/01/2014 and 12/31/2015. An extended Cox Model using time-dependent covariate and landmark analysis was conducted for ALC to predict separately CMV infection and rejection.
*Results: The population consisted of 381 kidney transplant recipients. CMV seropositivity for both donors and receipients was 50%; 19% were CMV D+/R- mismatches, 51% were CMV R+, while 30% were CMV D-/R-. Induction immunosuppressive regimens were roughly equally divided among basiliximab, alemtuzumab and thymoglobulin. In an extended Cox model using time-dependent covariate, ALC studied as a binary variable with a cut-off of 610 cells/uL was associated with development of CMV infection (when ALC<610 cells/uL) with a HR of 2.25 (CI 1.02-4.96; p=0.043) and 2.91 (CI 1.09-7.77; p=0.033) for all CMV at-risk serostatus and mismatches (D+R-), respectively.
However, time-dependent cox model did not show significant association between ALC and rejection (HR 1.2 (CI: 0.76-1.9; p=0.434)
In contrast, basiliximab induction was significantly associated with rejection (p=0.012).
*Conclusions: ALC, a simple and readily available measure, could predict subsequent CMV infection. An ALC of <610 cells/uL was associated with increased risk of CMV infection. In contrast, an ALC value associated with higher risk of rejection cannot be determined. Hence, a “safety corridor” could not be defined.
To cite this abstract in AMA style:Elhelou G, Lahr B, Razonable R. Absolute Lymphocyte Count: Is There a “Safety Corridor?” [abstract]. Am J Transplant. 2020; 20 (suppl 3). https://atcmeetingabstracts.com/abstract/absolute-lymphocyte-count-is-there-a-safety-corridor/. Accessed July 28, 2021.
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