STABLE ENGRAFTMENT OF ALLOGENEIC LYMPHOCYTES-T IN A PATIENT WITH SEVERE COMBINED IMMUNODEFICIENCY FOLLOWING A TRANSFUSION WITH UNIRRADIATED BLOOD - SPECIFIC RECOGNITION OF HOST HISTOCOMPATIBILITY ANTIGENS AND ENGRAFTMENT FAILURE OF A BONE-MARROW TRANSPLANT HLA-IDENTICAL TO THE HOST

We have analyzed the immunocompetence of blood donor-derived, allogeneic T cells that had engrafted in a patient with severe combined immunodeficiency following transfusion with unirradiated blood. The blood donor T cells multiply and persist in the patient's bone marrow and peripheral blood over several months without leading to a graft-versus-host disease. The allogeneic T cells can be expanded in vitro and restimulated by cells expressing host HLA-Dr antigens. The presence of blood donor-derived T cells prevented engraftment of a bone marrow graft from an HLA-identical sibling; in contrast, engraftment and immunological reconstitution by bone marrow donor-derived cells was seen following elimination of the allogeneic T cells in vivo. We conclude that the allogeneic T cells sensitized against host histo-compatibility antigens were responsible for bone marrow graft failure, even though this sensitization did not lead to a graft-versus-host disease.