CD28 and polymyositis: Our research has identified potential roles for various CD8+ T cell subsets, including effector memory CD8+ T cells, CD8+ CD28+ CD45RA‐ T cells, naive CD8+ T cells, CD28+ CD45RA‐ CD8+ T cells, and CD28‐ CD8+ T cells in polymyositis, though the specific mechanisms underlying these roles remain to be further investigated.