The PD-1 immune checkpoint is essential for self-recognition by the immune system, with disruption of the pathway associated with several autoimmune disorders. However, the involvement of PD-1 and its ligand PD-L1 in muscle-weakening autoimmune disease myasthenia gravis is unclear. Now, researchers have linked increased PD-L1 expression in the muscles of myasthenia gravis patients with disease severity and shown that this could ultimately help control the immune response and modulate disease symptoms.