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