Castration significantly increases the efficacy of BMT in reducing clinical disease. Young 8- to 12-week-old C57Bl/6 treated at day 12 after EAE induction with BMT only (n = 43) showed a significant reduction in clinical disease compared with untreated EAE mice (n = 31), whereas the mice treated with BMT in combination with castration (n = 43) displayed even further amelioration of disease. Results are expressed as mean plus or minus SEM from 2 or more independent experiments. *P < .05 versus BMT only; ∧P < .05 versus EAE untreated.