[In vivo detection of alloreactive T cells of host origin after rejection of HLA-identical allogeneic bone marrow transplant].

Rejection and graft vs host disease after HLA-identical allogeneic bone marrow transplantation are probably due to in-vivo T-cell reactivity against non-MHC antigens. Peripheral blood lymphocytes from a patient transplanted for aplastic anemia have been obtained during graft failure and tested for their alloreactivity towards unrelated and marrow donor lymphocytes. Their caryotype was determined. Our results demonstrate (1) alloreactive T cells of host origin and (2) the presence of donor-specific host cells in vivo, providing evidence for rejection following in vivo sensitization to non-MHC antigens.