Programmed cell death ligand 1 expression is upregulated in the skeletal muscle of patients with myasthenia gravis.

We investigated the expression patterns of programmed cell death-ligand 1 (PD-L1) in the skeletal muscle of 15 patients with myasthenia gravis (MG). In 11 of the patients, immunohistochemistry confirmed the localization of PD-L1 in the muscle cell membrane with cytoplasmic integrity. PD-L1 mRNA expression levels were higher in the muscles of MG patients as compared to those of non-myogenic patients (p < .05). Moreover, a unimodal relationship between PD-L1 mRNA levels and quantitative MG scores for disease severity was identified by a generalized additive model, indicating reciprocal effects. Together, these results suggest that MG symptoms might influence PD-L1 expression in muscle cells, and upregulated PD-L1 expression might inhibit autoimmune reactivity.