CD4 and antisynthetase syndrome: In immune-mediated necrotizing myopathy (IMNM), expanded CD8 T cells markedly reduce autoreactive CD4 T cells via enhanced cytotoxicity (66); in antisynthetase syndrome treated with CD19-targeted CAR T cells, declines in disease-associated serum markers (including anti Jo 1) and peripheral B cells were observed, with a transient CAR T peak on day 7 and a drop by day 14, suggesting limited durability of response; preconditioning included fludarabine and cyclophosphamide in the days preceding CAR T infusion, and MRI demonstrated radiological improvement post-treatment.