In this review, we summarize current knowledge of the astrocytic changes and behaviour in both MS and experimental autoimmune encephalomyelitis (EAE), and the contribution of pathogenic Th1, Th17 and Th1-like Th17 cell subsets, and CD8+ T cells to the morphological and functional modifications occurring in astrocytes and their pathological outcomes. The gene discussed is CD8A; the disease is myeloid sarcoma.