Correlation of CD34+ cell yield in peripheral blood progenitor cell product with the pre-leukapheresis cell counts in peripheral blood.

INTRODUCTION: Accurate timing of the leukapheresis procedures is of paramount importance to get the best possible CD34+ cell yield in the minimum number of leukapheresis procedures. AIM: To find if pre-harvest CD34+ cell concentration in peripheral blood correlates with CD34+ cells in the product. MATERIAL AND METHODS: Sixty Leukapheresis procedures were performed for 25 patients (8 autologous and 17 allogeneic transplants) with hematological malignancies. Statistical analysis was performed to correlate the pre-harvest CD34+ cell count and the CD34+ cell yield. Volume processed during PBPC harvests was three times the blood volume. RESULTS: The best correlation was found between the leukapheresis product CD34+ cell count and the pre-harvest PB-CD34+ cell count (PCC=0.674) when compared with the other pre-harvest PB cell counts viz., WBC (PCC=0.229) and MNC (PCC=0.324). This correlation was better in the allogeneic harvest (PCC = 0.645) than the autologous harvest procedures (PCC = 0.348). Correlation analysis based on paired samples from the 60 leukapheresis procedures showed that when the pre-leukapheresis PB-CD34+ cell count was >20x10(3)/ul a yield of >1x10(6) CD34+ cells/Kg could be obtained in 95% of the cases and >2x10(6) CD34+ cells /Kg could be harvested in 68% of cases whereas when the pre-leukapheresis PB-CD34+ cell count was <5x10(3)/microl the yield was <1x10(6) CD34+ cells/Kg in 81% of the procedures. CONCLUSION: The yield of CD34+ cells in PBPC harvests depends on the pre-harvest CD34+ cell concentration and therefore it is more useful than the pre-harvest WBC or MNC counts for predicting the appropriate timing of the harvests and also to achieve the best possible yield of CD34+ cells.

Plasma exchange for thrombotic thrombocytopenic purpura following hematopoietic stem cell transplantation.

A 17 years old female diagnosed with acute myeloid leukemia (AML)-M2 received an allogeneic haematopoietic stem cell transplant (HSCT) and was given graft versus host disease (GVHD) prophylaxis with methotrexate, cyclosporin-A (CsA) and methyl prednisolone. On day +42 post-transplant, she was diagnosed to have thrombotic thrombocytopenic purpura (TTP). Therapeutic plasma exchange (TPE) (40 ml/kg body mass) using fresh frozen plasma was performed on 8 consecutive days. The renal function, LDH levels, platelet count and peripheral smear findings improved but the neurological symptoms persisted even after TPE. Few reports are available in literature on the effectiveness of therapeutic plasma exchange (TPE) in post-bone marrow transplant (BMT) TTP. The good hematologic response achieved in this patient suggests that TPE could be life-saving and should be tried in every patient with post-BMT TTP.