The expression of Programmed death ligand 2 in patients with thymoma and thymomatous Myasthenia Gravis

Abstract

Background There is a growing relationship between PD-1/PD-Ls and autoimmune disease We attempted to explore the relationship of the PD-L2 expression in patients with thymoma, especially with Myasthenia Gravis (thymomatous MG).Methods Seventy patients with thymoma who underwent surgical resection between January 2017 to December 2018 were retrospectively reviewed. The PD-L2 expression was evaluated by immunohistochemistry. The association between the PD-L2 expression and the clinicopathologic features was investigated, especially thymomatous MG. Results The PD-L2 expression was positive in 41 patients (58.6%) and negative in 29 patients (41.4%). The PD-L2 expression was significantly associated with WHO histology of type B2 and B3 thymoma (p=0.008) and the status of MG (p=0.002). In addition, PD-L2 positive tumors showed a significantly smaller tumor size (P=0.017). Ectopic thymus was significantly more often seen in the PD-L2 positive group (p=0.035). The patients with MG (p=0.001) and WHO type B2 and B3 (p=0.007) have significantly higher PD-L2 scores. Multivariate logistic regression model showed the status of MG (OR 12.601, 95%CI 2.406-65.995, p=0.02) and age (OR 0.199, 95%CI 0.046-0.863, p=0.031) were significantly associated with the expression of PD-L2. The analysis of 33 patients with MG shows age was not associated with the expression of PD-L2 (OR 0.04, 95%CI 0.001-3.2, p=0.15). Conclusions A strong expression of PD-L2 in thymoma was significantly associated with thymomatous MG and WHO histologic type B2 and B3. In addition, PD-L2 may play a potential role in the pathogenesis of thymomatous MG.