Pure Red Cell Aplasia In Major ABO Mismatched Allogeneic Hematopoietic Cell Transplantation Is Associated With Severe Pancytopenia

The persistence of anti-donor isohemagglutinins in Major ABO mismatched allogeneic stem cell transplantation (HCT) leads to pure red cell aplasia (PRCA). In our previous report of 12 patients with PRCA, severe pancytopenia was observed in one patient who eventually had a second transplant (Aung et al. B J Haematol 2013 Mar; 160(6):798-805). Furthermore, ABO antigens are expressed on or adsorbed from plasma on granulocyte and platelets and these may be affected by isohemagglutinins. To further investigate this observation we analyzed a larger cohort of patients with PRCA to determine the frequency of pancytopenia and natural history of pancytopenia in patients with PRCA after Major ABO incompatible HCT.

We reviewed 758 patients who received a Major ABO-mismatched HCT between January 2003 and December 2012 at our institution. Pure red call aplasia was determined to be present when the bone marrow biopsy on post-transplant day 30 demonstrated absent or nearly absent erythroid precursors with absence of donor red cells on forward red cell typing of the recipient and the recipient being red cell transfusion dependent. Pancytopenia was defined as ANC < 1.5 x 10⁹/L or requiring G-CSF, Platelets < 50 x 10⁹/L or transfusion dependent, and PRCA with red cell transfusion dependence as above at 90 days after allogeneic SCT.

83 patients had PRCA. Of these 16 (19%) had pancytopenia at day 90 after transplant. None of these patients had any other reason for persistent pancytopenia like CMV or other viral infection or use of drugs like ganciclovir or disease recurrence. On post-transplant day 90, median absolute neutrophil counts (ANC) was 1.01 K/UL with 15 (94%) patients having intermittent G-CSF and median platelet count was 14 KL/UL (range 6-49) with 13(81%) patients platelet transfusion dependent. All patients were red cell transfusion dependent. Of the 16 PRCA patients with pancytopenia, 2 (12%) received a second transplant due to persistent pancytopenia/graft failure and 2 (12%) relapsed. 2 (12%) patients have still not recovered their platelet counts despite red cell and ANC recovery.

In the remaining 10 (63%) patients, neutropenia and thrombocytopenia resolved after resolution of PRCA. Red cell recovery occurred at a median of 226 (95-549) days post transplant, ANC recovered at median of 325 (105-1080) days post-transplant, and Platelets recovered at median of 296 (94-2738) days post-transplant.

Severe pancytopenia is frequently (19%) associated with PRCA in Major ABO incompatible HCT. Neutropenia and thrombocytopenia resolve after resolution of red cell aplasia in the majority of patients.

Andersson:Otsuka Pharmaceuticals: Research Funding. Qazilbash:Celgene: Membership on an entity’s Board of Directors or advisory committees; Millennium: Membership on an entity’s Board of Directors or advisory committees. Shah:Celgene: Membership on an entity’s Board of Directors or advisory committees, Research Funding.