Longitudinal analysis of immune function in the first 3 years of life in thymectomized neonates during cardiac surgery

Abstract

SummaryThe 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) Vb 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.

Lymphopenia-Driven Homeostatic Regulation of Naive T Cells in Elderly and Thymectomized Young Adults

“…Thereafter, it was shown that low T cell frequencies were associated with high levels of IL-7 in sera from HIV patients (45, 46) as well as patients with cancer chemotherapy-associated lymphopenia (29), and children following thymectomy (31). In this study, we extend these observations to elderly and YATEC, who thus present elevated circulating IL-7 levels.…”

“…Next, we analyzed IL-7 plasma levels and signaling in elderly and YATEC. IL-7 plasma levels are known to be elevated in HIV-infected patients with lymphopenia (7) as well as in children following thymectomy (31,32). The situation in older thymectomized patients and in elderly is less clear.…”

Long-term restoration of the human T-cell compartment after thymectomy during infancy: a role for thymic regeneration?

“…[14][15][16][17][18] In pediatric cardiac surgery, thymectomy is performed to gain an unrestricted view of the operation site. Especially in neonates, in whom the thymus is relatively large, surgical procedures involving the large vessels necessitate complete removal of the thymus.…”

Risk factors of sepsis after open congenital cardiac surgery in infants: a pilot study

“…32 Decreased in number and function of T lymphocytes has been postulated to be one of the causes of sepsis after open cardiac surgery with thymectomy. 33 Our study, on the contrary, did not observe a significant relation between sepsis rate and thymectomy (RR=0.481, p=0.157).…”

“…The incidence of postsurgical immunodeficiency, recurrent infections, neoplasm, or autoimmune reactions was also not significantly related with thymectomy procedures. 32,34,35 This occurrence might be explain by an incomplete thymectomy, release of mature T cells before the procedure, compensatory increase in the nonspecific immune responses such as neutrophils and natural killer cells, and activation of other reticuloendothelial cells. 34 Failure to thrive and poor nutritional status have been considered as one of the major problems in children with congenital cardiac anomaly.…”