Lack of H-2 restriction of suppressor factor specific to myelin basic encephalitogen

A cell-free extract has been prepared from spleen cells of (SJL/J x BALB/c)F1 mice which were rendered non-susceptible to EAE by treatment with mouse spinal cord homogenate in incomplete Freund's adjuvant. Such extract has been previously shown to have suppressive activity on the induction of EAE, as well as on the immune response in syngeneic mice towards the mouse basic protein. We have now demonstrated that this factor is as effective in several other strains of mice, of different H-2 haplotype. The activity of this factor was manifested both in vivo by inhibiting the DTH response to MBE in the various mouse strains, and in vitro, by blocking the MIF activity of the allogeneic lymphocytes. A suppressor factor was prepared by a similar procedure from the EAE-resistant BALB/c mice. This factor was as active as the factor from the (SJL/J x BALB/c)F1 hybrid in blocking the anti-MBE antibody binding to MBE. It is also suppressive, and it inhibited the DTH response to MBE in both syngeneic and semi-allogeneic (SJL/J x BALB/c)F1 mice. It is thus demonstrated that the MBE-specific soluble suppressor factor involved in the EAE system in mice shows no indication of H-2 restriction.