Notably, 10 immune cell traits demonstrated protective roles in the occurrence of polymyositis (OR < 1, P < .05): B cell panel: IgD‐ CD38dim AC; cDC panel: CD11c on granulocyte and CD80 on CD62L+ myeloid DC; maturation stages of T cell panel: CD8 on effector memory CD8+ T cell and CD45RA‐ CD4+ %CD4+; monocyte panel: CD40 on monocytes; TBNK panel: CD45 on CD4+, HLA-DR+ NK AC, and SSC-A on HLA-DR+ NK; Treg panel: CD8 on CD28+ CD45RA‐ CD8+ T cell. Here, SELL is linked to polymyositis.