by Tokyo Medical and Dental University PD-1+CD8+ T cells were activated rather than exhausted. PD-1+CD8+ T cells infiltrated muscle tissues. Affected muscles reacted to IFNγ, which could be produced from effector T cells, as a danger signal and then expressed PD-L1. Muscles countered PD-1+CD8+ T cell attacks through the enhancement of PD-L1 expression. Credit: Department of...