CYTOTOXIC T LYMPHOCYTE ANTIGEN 4-IMMUNOGLOBULIN FUSION PROTEIN COMBINED WITH METHOTREXATE/CYCLOSPORINE AS GRAFT-VERSUS-HOST DISEASE PREVENTION IN A CANINE DOG LEUKOCYTE ANTIGEN-NONIDENTICAL MARROW TRANSPLANT MODEL1

Abstract

We studied whether blocking of the T cell costimulatory signal from B7-->CD28 by cytotoxic T lymphocyte antigen 4-immunoglobulin fusion protein would, either by itself or when added to methotrexate/cyclosporine, result in improved graft-versus-host disease prevention after dog leukocyte antigen nonidentical canine hematopoietic stem cell transplantation after 920 cGy total body irradiation. Survivals of cytotoxic T lymphocyte antigen 4-immunoglobulin fusion protein-treated dogs were only slightly prolonged over controls. It appeared that the addition of cytotoxic T lymphocyte antigen 4-immunoglobulin fusion protein failed to induce graft-host tolerance in this model beyond that achieved with methotrexate/cyclosporine alone.