Abstract
Thymectomy is an established treatment in adult MG and also recommended for the treatment of post-pubertal onset juvenile MG. Whether the youngest children should be thymectomized is still debated. Signs of premature aging of the immune system have been shown in studies on early perioperative thymectomy in children with congenital heart defect. In this retrospective cohort study the objective was to investigate the long-term effects of treatment related thymectomy on T cell subsets and T cell receptor rearrangement excision circles (TRECs) in peripheral blood of juvenile myasthenia gravis (MG) patients, as well as clinical occurrence of autoimmune disorders, malignancies and infectious diseases. Forty-seven patients with onset of myasthenia gravis before the age of 19 years were included; 32 (68.1%) had been thymectomized and 15 (31.8%) had not. They were studied at varying times after thymectomy (7–26 years). We found a significant lower number of naïve helper T cells (CD4+CD45RA+) with an increased proportion of memory helper T cells (CD4+CD45RO+), and a significant lower number of naïve cytotoxic T cells (CD8+CD27+CD28+) in the thymectomized patients. In addition they showed a significant reduction in the number of TRECs and proportion of recent thymic emigrants (RTE) compared to non-thymectomized patients. In none of them an increased frequency of malignancies or infections was found. Our findings indicate a premature aging of the immune system after thymectomy in juvenile MG, but associated clinical consequences could not be verified.
Highlights
Juvenile myasthenia gravis (MG) is a rare autoimmune disorder giving fatigable muscle weakness due to immunological destructions at the endplate of the neuromuscular junction
In this study we find that thymectomy in juvenile MG patients results in significant alterations in the peripheral T cell subsets, especially in the CD4+ subset with a decrease in naïve helper T cell with a relative increase in memory helper T cells, and a decrease in naïve cytotoxic T cells
All though indications for a premature immunosenescence in the T cell compartment in thymectomized juvenile MG patients, we could not show any clinical consequences in our population at last follow up
Summary
Juvenile myasthenia gravis (MG) is a rare autoimmune disorder giving fatigable muscle weakness due to immunological destructions at the endplate of the neuromuscular junction. In the latest international consensus guidelines for the management of MG, thymectomy is recommended for the treatment of postpubertal onset juvenile MG [7]. It is still debated, whether the youngest children should be thymectomized. Atrophy and reduction of thymus activity start early in life, and its role after the initial T cell production is not clear [8]. Studies on early perioperative thymectomy in children with congenital heart defects have shown signs of premature aging of the immune system, especially the T cell compartment [9,10,11].
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