Marrow graft studies in dogs: factors influencing resistance to engraftment and graft-versus-host disease.

Our studies have provided further data to support the concept of resistance to engraftment in the dog. Resistance seems to be mediated by antigens coded for by loci different from but linked to DLA. Resistance can be abrogated by the addition of viable lymphoid cells to the marrow inoculum, by high-dose (fractionated) TBI of the recipient and by MTX given postgrafting. CyA has an adverse effect on engraftment probably by interfering with the graft-facilitating effect of donor lymphocytes. GVHD following allogeneic marrow transplantation appears to be mediated by DLA and non-DLA antigens. GVHD can be prevented or ameliorated in recipients of DLA identical littermate marrow by postgrafting CyA or MTX. With DLA nonidentical or unrelated grafts MTX or even more so a combination of MTX and CyA appear to be able to induce tolerance in some recipients.