Suppressor T cells prevent experimental autoimmune encephalomyelitis in mice

Immune suppression (immunoprotection) in experimental autoimmune encephalomyelitis (EAE) was studied in (SJL X BALB/c)F1 mice using inocular of mouse spinal cord homogenate (MSCH), or mouse basic protein of myelin (M-BPM), in Freund's incomplete adjuvant (FIA). Such immunization specifically recruited lymphoid cells which markedly suppressed the capacity of effector lymph node cells from appropriately immunized syngeneic mice to transfer adoptively EAE. Suppression was demonstrable with transfer of bone marrow and spleen cells, but not with lymph nodes or thymus cells. Adoptively transferred suppression was maximal when cells were injected 9-30 days after the suppressive injection. Inhibition of EAE by suppressor cells was specific for the relavant antigen BPM, and required viable cells. Treatment of cells with anti-Thy-1 serum before transfer abolished their suppressor activity. After adoptive transfer of suppressor cells into syngeneic recipients subsequently immunized for EAE, there was inhibition of EAE and reduced cell-mediated immune response to BPM as judged by macrophage migration inhibition assays. Hence, in mice at least, immuno-protection against EAE is explicable by recruitment of suppressor T lymphocytes with the dual capacities of inhibiting development of effector T cells after antigenic stimulation, and of blocking their damaging effects on the antigen in the central nervous system.