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.
Methods
Blood samples from ACHD with early thymectomy ≤ 1 year of age (ACHD-ET; n = 12), no thymectomy (ACHD-NT; n = 8), and healthy controls (HC; n = 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%, p = 0.027 and 37.2% vs. 57.4%, p = 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 (p < 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.