NKT cells are observed in muscles from patients with Duchenne muscular dystrophy and are depleted from mdx muscle and liver by GM1 treatment. (A) Cross sections from DMD biopsies were immunostained with an antibody against Vα24, the invariant chain of human NKT cells. Positive staining appears red, and counterstain with hematoxylin labels the nuclei dark blue and the muscle tissue light blue. Bar, 100 µm. (B) Quantification of liver and muscle NKT cells from GM1- or PBS-treated animals. The graph shows a representative experiment in which each bar represents the values obtained from pooled muscles isolated from three mice injected with PBS (blue bars) and three mice injected with GM1 (black bars). The plot illustrates the frequency of CD3⁺ cells that coexpress either [NK1.1] or [NK1.1⁺ CD1d-tetramer]. Numbers shown represent the amount of depletion attained by GM1 treatment compared with PBS controls.