Different molecular expression in thymoma with ocular or generalized myasthenia gravis

Increasing evidence supports a link between expressions of CD4, CD25, Foxp3, and CXCL13 in thymic hyperplasia with myasthenia gravis (MG) patients. Herein, we investigated the expressions of these molecules in thymoma patients with ocular MG (OMG) or generalized MG (GMG).

A total of 58 thymoma patients with MG (23 GMG and 35 OMG) and 73 thymoma patients without MG were analyzed using immunohistochemistry for CD4, CD25, Foxp3 and CXCL13.

OMG was more frequent than GMG in late-onset thymoma males (P=0.037), but no difference was observed in females (P=0.128). There was no significant difference of Foxp3 expression among all types of thymoma from patients with OMG and Non-MG. Compared to patients with OMG, a decreased Foxp3 expression was seen in types AB, B1 and B2 thymoma with GMG, with the decrease in the former two types reaching significance (P=0.001, 0.043, respectively). However, a significantly increased expression of CXCL13 was observed in types B1 and B2 thymoma patients with GMG (P=0.027, 0.048, respectively, compared to those with OMG). Furthermore, the CXCL13 expression in type AB thymoma patients with GMG was higher than those with Non-MG (P=0.003).There were no differences among expressions of CD4, CD25, Foxp3, and CXCL13 in type A and B3 thymoma patients, regardless of with OMG, GMG or Non-MG.

Differential expressions of Foxp3 and CXCL13 in various types of thymoma patients with OMG or GMG might suggest the differential immunological processes underlying the two subtype of MG.