“…Matching of donor and recipient at the major histocompatibility locus re duces severity and incidence of GVHD in rodents, dogs and man [15,20,25]. Posttransplantation immunosuppression by drugs has been investi gated as an additional approach [5,16,21,25,29], Methotrexate (MTX) was shown to increase posttransplantation survival in mice and dogs [24,27] if given early after transplantation and on a prolonged schedule [14,18].…”