Fluctuating lymphocyte chimerism, tolerance and anti-tumor response in a patient with refractory lymphoma receiving nonmyeloablative conditioning and a haploidentical related allogeneic bone marrow transplant.

A 51-year-old patient with refractory non-Hodgkin lymphoma (NHL) received non-myeloablative conditioning and a two of six (A, B, DR) human leucocyte antigen (HLA) mismatched donor BMT. Post-BMT lymphocytes showed fluctuating T- and natural killer (NK)-cell chimerism, which culminated in mainly donor lymphocytes by Day + 100. Changes in lymphocyte chimerism correlated with anti-donor and anti-host responses in mixed lymphocyte reaction (MLR). On Day + 100, a strong anti-host response was observed in MLR in the absence of graft-versus-host disease (GVHD), together with near complete regression of the patient's lymphoma. A mild chronic GVHD later developed and, eventually, by 680 days post-BMT, the lymphoma had relapsed and MLR reflected a state of global immune unresponsiveness. These observations demonstrate evolving host-versus-graft and graft-versus-host tolerance that correlates with fluctuating lymphoid chimerism and graft-versus-lymphoma (GVL) effects, in the absence of severe GVHD. Eventual lymphoma relapse temporally correlated with a generalised immunosuppressed state.