NK and Th17 Cells in The Thymus of Myasthenia Gravis Patients

Abstract

Objective: As a classical autoimmune disorder, anti-acetylcholine receptor antibody positive myasthenia gravis has an unconventional pathophysiology that involves thymus, the central organ for immune tolerance induction. Both natural cells and type 17 helper T (Th17) cells possess capacity to influence autoimmune inflammation. This study aims to determine the presence of Th17 and natural killer cells in the thymus from myasthenia gravis patients. Materials and Methods: Thymectomy materials of myasthenia gravis patients and non-myasthenic controls were assessed by CD56, CD16, CD2, CD3, NKG2D, NKp46 and IL-23R flow cytometry and IL-23R, IL-21R, and ROR-γ immunohistochemistry. Results: Even though natural killer cell infiltration was limited, the majority of these cells displayed activation markers NKG2D and NKp46. Expectedly, the amount of CD2+ lymphocytic cells were higher than CD3+ thymocytes in which a considerable percentage was carrying the receptor for IL-23 (IL-23R). In addition to IL-23R, IL21R, and ROR-γ were also detected in myasthenic thymus as a marker related to Th17 cells. These Th17-related markers were reduced in thymoma compared to that of detected in thymic hyperplasia or the myasthenic thymus with normal histopathology. Conclusion: Both natural killer cells and Th17 cells are found in the myasthenic thymus indicating a possible cross-regulation between these cell types that may influence the course of autoimmune reactions.