How does neonatal thmectomy affect the immune system?

BACKGROUND: The aim of this study was to determine the effects of neonatal thymectomy on the immune system in later life. METHODS AND RESULTS: Immune system tests were performed in 26 children at 1 year of age. Thirteen of them had been operated for transposition of the great arteries and had thymectomy in the same operation in the neonatal period. Thirteen control subjects were normal. Immune system tests including white blood cell count, lymphocyte count, T and B cells subgroups (CD2, CD4, CD5, CD7, CD8, CD16, CD20, CD22, CD56), mitotic reaction to phytohaemagglutinin in lymphocyte culture. White blood cell count and lymphocyte count were performed. In the statistical analysis, Mann-Whitney U and Wilcoxon rank sum W tests were used for both groups. Statistical significance was taken at a value of P < 0.05. There was no significant difference in mean white blood cell count, mean blastic transformation reaction of lymphocytes to phytohaemagglutinin, and CD7, CD4/CD8, CD20, CD22, CD56 ratios between the two groups (P > 0.05). Significant differences in mean lymphocyte number, and CD2, CD4, CD5, CD8, CD16 ratios between the two groups were defined (P < 0.05). CONCLUSIONS: In our study, it was noticed that mainly T lymphocyte subgroups were effected by neonatal thymectomy. Although no infection requiring therapy was seen in the thymectomized patients, we advise to limit total thymectomy as much as possible in neonatal heart operations.