The correlation of the levels of interleukin-15 with late onset myasthenia gravis

Abstract

Objective To investigate the relationship between the plasma level of interleukin 15 (IL-15) and the quantitative myasthenia gravis (QMG) score in late-onset myasthenia gravis (MG). Methods The blood samples of 86 patients (over 50 years old) who admitted to Henan Provincial People′s Hospital between 2010 and 2016 were collected at two different stages: pre-treatment and six months post-treatment. The diagnosis was verified by characterizing clinical manifestation, neostigmine testing, electromyographic recording, thymic imaging and plasma anti-acetylcholine receptor (AchR). All the patients were divided further by modified Osserman classification and treated with cholinesterase inhibitor and glucocorticoid. The blood samples of 42 healthy controls were also collected from their physical examination at the end of 2016. Enzyme linked immunosorbent assay was used to evaluate the levels of IL-15 in plasma. Thymectomy was performed on patients with MG accompanied by thymoma. The possible correlation between the expression of IL-15 and the QMG scores, different types were analyzed. Results Before treatment, the levels of IL-15 in the plasma were much higher in the late onset MG patients (both ocular and generalized) than in the healthy controls ((5.75±1.57) pg/ml vs (4.40±0.50) pg/ml, t=2.925, P 0.05) and in the severe type of late-onset MG patients without thymoma, the IL-15 level was mildly increased ((4.76±0.75) pg/ml vs (4.40±0.50) pg/ml, t=2.462, P 0.05). IL-15 and QMG scores returned to normal six months after treatment. Conclusions IL-15 is increased in the plasma of late-onset MG patients, and is positively correlated with the QMG scores, especially in the late-onset MG patients with thymoma. In addition, IL-15 is decreased upon the therapy in the MG patients. Key words: Myasthenia gravis; Interleukin-15; Thymoma; Retrospective studies