Influence of the hematopoietic stem cell source on early immunohematologicreconstitution after allogeneic transplantation

Several acute hemolysis episodes, sometimes lethal, have been recently desc ribed after transplantation of allogeneic peripheral blood hematopoietic st em cells (PBHSCs). Hemolysis resulted from the production of donor-derived antibodies (Abs) directed at ABO antigens (Ags) present on recipient red bl ood cells (RBCs). A multicenter randomized phase III clinical study compari ng allogeneic PBHSC transplantation (PBHSCT) versus bone marrow hematopoiet ic stem cell transplantation (BMHSCT) has been conducted in France. In the course of this study, serum anti-A and/or anti-B Ab titers were compared be fore the conditioning regimen and on day +30 after transplantation in 49 co nsecutive evaluable PBHSCT (n = 21) or BMHSCT (n = 28) recipients. PBHSCT r esulted in a higher frequency of increased anti-A and/or anti-B Ab titers 3 0 days after transplantation as compared to BMHSCT: 8 (38%) of 21 versus 3 (11%) of 28 (P = .04). In PBHSCT recipients, increased titers were observed mostly after receiving a minor ABO mismatch transplant: 5 of 7 versus 3 of 14 in the absence of any minor ABO mismatch (P = .05), whereas this was no t the case after BMHSCT: 1 of 8 versus 2 of 20. Anti-A and/or anti-B serum Abs detectable at day +30 after PBHSCT were always directed against A and/o r B Ags absent both on donor and recipient RBCs. Finally, 3 of 21 PBHSCT ve rsus 0 of 28 BMHSCT recipients developed anti-allogeneic RBC Abs other than ABO (P = .07). Overall, the data strongly suggest that immunohematologic r econstitution differs significantly after granulocyte colony-stimulating fa ctor-mobilized PBHSCT when compared to BMHSCT. Such a difference could cont ribute to the acute hemolysis described after PBHSCT as well as to distinct alloreactivity after PBHSCT. (Blood, 2001;97: 2580-2586) (C) 2001 by The A merican Society of Hematology.