Thus, B-cells may contribute to the pathogenesis of MS and neuronal tissue damage through multiple mechanisms, including (1) antibody production, (2) antigen presentation, (3) modulation of the T-cell response, (4) activation and proliferation of auto-proliferative CD4+ T-cells in the CNS, (5) pro-inflammatory cytokine and chemokine production, and (6) compartmentalisation of pathological processes. The gene discussed is CD4; the disease is myeloid sarcoma.