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Longitudinal analysis of immune function in the first 3 years of life in thymectomized neonates during cardiac
E Mancebo1, J Clemente, J Sanchez
1Servicio de Inmunología, Hospital Universitario 12 de Octubre, Madrid, Spain.
Insights
Neonatal thymectomy, the removal of the thymus in newborns, leads to a lasting decrease in T lymphocytes, crucial for immune function. This early surgical intervention may impact long-term immune system capacity, particularly T cell reconstitution.
Area of Science:
- Immunology
- Neonatal Surgery
- Congenital Heart Disease
Background:
- The thymus is vital for T cell development and immune system maturation.
- Neonatal thymectomy is sometimes performed during congenital heart disease interventions.
- The long-term immunological consequences of neonatal thymectomy require further investigation.
Purpose of the Study:
- To evaluate the long-term effects of neonatal thymectomy on immune system function.
- To assess lymphocyte populations, T cell receptor diversity, and immune responses in neonatally thymectomized subjects.
- To investigate correlations between immune parameters and thymectomy status.
Main Methods:
- Evaluation of lymphocyte populations (naive, memory, effector), T cell receptor (TCR) Vbeta repertoire, and immunoglobulin levels.
- Measurement of T cell response to mitogen stimulation, TCR excision circles (TRECS), and interleukin-7 (IL-7) levels.
- Longitudinal assessment of 23 subjects who underwent thymectomy within 30 days of life, up to 3 years of age.
Main Results:
- Neonatal thymectomy resulted in a significant long-term decrease in total lymphocyte counts, particularly naive CD4+ and CD8+ T cells.
- Reduced levels of TRECS and elevated plasma IL-7 were observed, indicating impaired thymopoiesis.
- A negative correlation between CD4+ T cells and IL-7 levels suggests a potential compensatory mechanism or consequence of thymic absence.
Conclusions:
- Neonatal thymectomy leads to a persistent reduction in T lymphocyte levels and TRECS, confirming the cessation of thymopoiesis.
- While immediate infectious complications were not increased, long-term immune function may be compromised, especially concerning T cell reconstitution.
- Further monitoring is crucial for individuals who have undergone neonatal thymectomy to understand potential risks for future immune challenges.
Abstract:
The purpose of this study is to evaluate the effects of neonatal thymectomy in the functional capacity of the immune system. We selected a group of 23 subjects, who had undergone thymectomy in their first 30 days of life, during an intervention for congenital heart disease. Several parameters of the immune system were evaluated during their first 3 years of life. Lymphocyte populations and subpopulations (including naive, memory and effector subpopulations), T cell receptor (TCR) Vbeta repertoire, response of T cells following in vitro stimulation by mitogen, quantification of immunoglobulins, TCR excision circles (TRECS) and interleukin (IL)-7 were measured. We found that neonatal thymectomy produces long-term diminution in total lymphocyte counts, especially in naive CD4+ and CD8+ T cells. Additionally, TRECS were decreased, and plasma IL-7 levels increased. A statistically significant negative correlation was found between absolute CD4+ T cells and IL-7 (r = -0.470, P = 0.02). The patients did not suffer more infectious events than healthy control children, but thymectomy in neonates resulted in a significant decrease in T lymphocyte levels and TRECS, consistent with cessation of thymopoiesis. This could produce a compromise in immune function later in life, especially if the patients suffer T cell depletion and need a reconstitution of immune function.
