Pre-Transplant Immunophenotyping in Pediatric Heart Transplant: A Role for the Immunologist?

Background: Pediatric heart transplant recipients are at risk for complications from prolonged exposure to immunosuppressive drugs, possibly worsened due to over-immune suppression in patients with pre-existing immune abnormalities.

Methods: This was a retrospective, single-center pediatric cohort study and review of baseline immune evaluation in patients referred for heart transplant. Referrals included were from January 1, 2021, to June 31, 2022.

Results: Fifty-one patients were referred during the time period with a median age of 5 years (ranging 1 month-20 years). Twenty-seven total patients were transplanted. Given a lack of standardized immune evaluation, results were focused on lymphocyte quantitation, functional testing when available, and T-cell subsets. Outcome measures focused on the number of infections and episodes of rejection requiring treatment. In total, 44.4% of patients experienced rejection, and the mean number of infections in the first 12 months post-heart transplant was 2.1 (range 0-7 total infections).

Conclusions: Baseline immune evaluation showed general T and B cell lymphopenia, without a clear connection between outcome differences for the number of infections or episodes of rejection requiring treatment. This small study demonstrated some differences in immune function in patients prior to heart transplant but was inadequately powered to draw conclusions about the effects of immunosuppression on post-transplant outcomes.