T Cell Response to Influenza Vaccination Remains Intact in Adults with Congenital Heart Disease Who Underwent Early Thymectomy.

Introduction: T cells developed in the thymus play a key role in vaccine immunity. Thymectomy occurs during infant congenital heart surgery and results in an altered T cell distribution. We investigated if adults with congenital heart disease (ACHD) who underwent early thymectomy have a diminished response to influenza vaccination.

Methods: Blood samples from ACHD with early thymectomy ≤ 1 year of age (ACHD-ET; = 12), no thymectomy (ACHD-NT; = 8), and healthy controls (HC; = 14) were collected prior to and 4 weeks after influenza vaccination. Flow cytometric analysis of T cell subsets and vaccine-specific cytokine expressing CD4 T cells as well as hemagglutination inhibition (HI) assays were completed.

Results: The mean age of the cohort was 34 ± 10.6 years and similar in all groups. The mean frequencies of naïve CD4 and CD8 T cells were lower in ACHD-ET than in HC (32.7% vs. 46.5%, = 0.027 and 37.2% vs. 57.4%, = 0.032, respectively). There was a rise in the frequency of memory CD4 and CD8 T cells in the ACHD-ET group. The ACHD-NT had no statistical difference from either group. The frequencies of influenza-specific memory CD4 T cells expressing IFN-γ and TNF-α were increased after vaccination across all groups ( < 0.05).

Conclusions: ACHD-ET have fewer naïve T cells, suggesting immunosenescence. Despite this, they show an adequate T Cell response to vaccination in young adulthood. Our findings support routine vaccination is effective in this population, but research into older ACHD is necessary.