Transient anti rhesus alloantibody produced by graft after non-myeloablative allogeneic stem cell transplant.

BACKGROUND: We report the case of a patient who received an allogeneic transplant with peripheral blood compatible ABO, Rhesus mismatched progenitor cells and who developed an asymptomatic transient anti Rhesus alloimmunisation. CASE REPORT: A 56-year-old man with renal cell carcinoma received a non-myeloablative allogeneic PBPC ABO compatible graft from his HLA-identical brother. Graft-versus-host disease prophylaxis consisted of cyclosporine alone. On day + 59, prior to any transfusion, a positive direct antiglobulin test (IgG++, C3d-) was detected. The indirect antiglobulin test (IAT) was considered doubtful, and IAT identification revealed the presence of an active anti Rhesus antibody (anti D specificity) in the patient's serum. This immunisation had no clinical consequence, with no acute hemolytic episode. Further monitoring showed negative antibody screening tests on day + 78. CONCLUSION: To our knowledge this is the first reported case of transient anti Rh (D) allo-immunisation after non-myeloablative allogeneic peripheral blood progenitor cell (PBPC) transplant. The period of occurrence and the specificity of this antibody strongly suggest a donor cell origin.