Asetilkolin Reseptör Antikoru Pozitif Myastenia Gravis Hastalarının Timektomi Materyallerinde Th17 Hücre İnfiltrasyonunun Değerlendirilmesi

Abstract

There is limited information on the role of Th17 cells in myasthenia gravis (MG) pathogenesis. Amount of Th17 cells in sera of acetylcholine receptor (AChR) antibody positive MG patients was believed to be associated with pathological subtypes of thymus. However, specific markers for those cells in thymus tissue, which is highly relevant to MG pathogenesis, have not been previously studied. In our study, we aimed to investigate the IL-21R, IL-23R and RORγ markers that are specific for Th17 cells, in thymus tissues of thymectomized AChR antibody positive MG patients. For this purpose, MG patients who applied to our clinic between 2000-2010 and underwent therapeutic thymectomy were retrospectively evaluated. The thymus tissues of 37 AChR antibody-positive MG patients and 24 control patients were selected. Thymus tissues of the patients were classified into three subgroups: thymoma (n=15), follicular hyperplasia (FH) (n=9) and normal thymus tissue (n=13). Immunohistochemical studies using each three antibodies (IL-21R, IL-23R and RORγ) revealed significantly less amount of staining in thymoma tissues of MG patients compared to other groups (FH, normal thymus and control) (p<0.05). In thymoma subgroup, a correlation between IL-21R and IL23R, as well as IL-23R and RORγ stainings were detected (rho=0.574, p<0.05). In MG patients, no correlation was found between staining intensity with each three antibodies and AChR antibody titers (p>0.05). These findings suggest that Th17 cells are relatively sparse in thymoma tissue and this contrasts with previously reported Th17 cell increase detected in sera of patients. Detachment of autoreactive Th17 cells from thymoma tissue and their transport to the peripheral circulation may account for these findings. Our study supports the idea that the pathogenic process may be different in MG patients with thymoma.