c-Rel expressed by the immune system but not the CNS is required for the development of EAE. Groups of C57BL/6 mice were immunized to induce EAE as described in Methods. Data presented are mean ± SEM of the disease scores. (a) Normal c-Rel+/+ mice (filled squares, n = 8) and c-Rel–/– mice (open circles, n = 8). (b) Irradiated c-Rel+/+ mice that were injected with c-Rel+/+ bone marrow cells (filled squares, n = 15) and irradiated c-Rel+/+ mice that were injected with c-Rel–/– bone marrow cells (open circles, n = 15). (c) Irradiated c-Rel–/– mice that were injected with c-Rel+/+ bone marrow cells (filled squares, n = 9) and irradiated c-Rel+/+ mice that were injected with c-Rel+/+ bone marrow cells (open circles, n = 8). The differences between the two groups in a and b are statistically significant (P < 0.002) as determined by Mann-Whitney test. Results are representative of two independent experiments.