CD8A and myeloid sarcoma: Myelin-specific CD8 T cells that are capable of killing neuronal cells in vitro have been isolated from MS patients (Tsuchida et al., 1994; Dressel et al., 1997; Medana et al., 2001; Crawford et al., 2004; Zang et al., 2004), which supports the hypothesis that CD8 T cells play a pathogenic role in the MS disease process.