Subgroup analysis 
A subgroup analysis was performed to assess the relationship between the expression levels of costimulatory molecules (mOX40/mOX40L and sOX40/sOX40L) and clinical parameters in patients with MG. Ninety patients with MG were divided into 5 subgroups according to sex, age of onset, MGFA classification, thymic histology, and AchR-Ab results. Specifically, significantly higher OX40 expression was observed on CD4+ T cells in the GMG group than in the OMG group and in patients with thymoma or thymic hyperplasia than in those without. No significant differences were observed between groups stratified by sex, age of onset or AchR-Ab levels. In terms of the expression of OX40L on CD19+ B cells in patients with MG, no statistically significant differences were observed between all subgroups. Regarding the expression of OX40L on CD14+mononuclear cells in patients with MG, the GMG group exhibited significantly higher expression than the OMG group, and significant differences were not observed between groups stratified by sex, age of onset, thymic histology and AchR-Ab levels. Results of the subgroup analysis of mOX40 and mOX40L levels in patients with MG are summarized in Table 2 .
The levels of sOX40 were significantly increased in patients with GMG compared to patients with OMG, and no significant differences were observed between groups stratified by sex, age of onset, thymic histology and AchR-Ab levels. However, in the analysis of the expression levels of sOX40L in patients with MG, no statistically significant differences were detected between all subgroups. Results of the subgroup analysis of sOX40 and sOX40L levels in patients with MG are presented inTable 3 .