Grant, Rhonda

Abstract Background: Previous studies have proposed combination of various factors that predict poor mobilization after GCSF stimulation. However, there is no single clinical or laboratory test that reliably correlates with bone marrow reserve and PBPC mobilization. Peripheral blood CD34+ cell count (pCD34) reliably correlates with PBPC mobilization and yield but only after GCSF administration. Methods: We have prospectively followed 36 autologous PBPC transplant candidates, from the time of initial evaluation to transplant, to evaluate factors the correlate with bone marrow reserve and autologous PBPC mobilization. Results: The patients median age was 63 (range 26 – 76). 21 of the 36 patients were diagnosed with dysproteinemia, primarily multiple myeloma, 10 patients had non-Hodgkin’s lymphoma while the remaining 5 had other form of hematological malignancies. Our evaluation shows baseline platelet count prior to growth factor administration significantly correlate with total CD34+ cell yield (spearman: r = 0.64, p <0.001, Figure 1). In addition, daily platelet count during PBPC harvest correlate with CD34+ cell yield for the day (spearman: r = 0.6, p <0.001). Using multiple linear regression model (F = 19.1, p <0.001, R2 = 0.64), we have determined patients’ age (p = 0.03) and type of disease (p <0.001), in addition to platelet count (p<0.001), significantly correlate with total CD34+ cell yield. Further analysis showed low baseline platelet count predicts poor PBPC mobilization. Using Receiver Operating Curve (ROC), we have determined that platelet count of 174,000/ul was the best cut-off for collecting at least 2 million/Kg CD34+ cells with sensitivity of 81% and specificity of 78% and estimated correct classification of 81%. Even though pCD34 counts were slightly more sensitive and were better at identifying poor mobilizers in our cohort (best cut-off 10/ul, sensitivity 96%, specificity 67%, correct classification 89%), their clinical utility were diminished since the values were only known after GCSF administration. Conclusion: Baseline platelet count is a sensitive predictor of bone marrow reserve and can be used prior to growth factor administration to predict poor mobilization. Figure 1: Correlation of baseline platelet count and total CD34+ cell yield Figure 1:. Correlation of baseline platelet count and total CD34+ cell yield

Abstract Transfusion of ABO-mismatched platelets is common practice. Although a unit of single donor apheresis platelet (SDP) contains as much plasma and passive anti-A or/and anti-B antibodies (allo-agglutinins) as a unit of fresh frozen plasma, ABO- mismatched platelet transfusions are considered safe and hemolytic transfusion reactions have only rarely been reported. We report a case of a 67-year old male, blood group A, with mantle cell lymphoma who received 1 SDP for chemotherapy induced thrombocytopenia. Several prior platelet transfusions had been uneventful. After 150 ml of irradiated, leukoreduced, SDP from blood group O donor had been infused, he developed nausea, light-headiness, chills, and back pain. He became bradycardic and hypotensive. Platelet transfusion was discontinued and intravenous dexamethasone and rapid saline infusion was administered. Later, his hemoglobin dropped from 10.6 to 7.4 g/dl and total serum bilirubin increased by 9 fold. A direct antiglobulin test (DAT) on post-transfusion sample demonstrated 1+ reactivity at room temperature. An elution test performed on the patient’s circulating red blood cells contained anti-A antibodies. These results are consistent with a severe acute hemolytic transfusion reaction. The donor anti-A and anti-B antibodies titers at room temperature and at 37°C were 512 and 2048 with A1 cells and 128 and 256 with B cells, respectively.This case illustrates the rare possibility of hemolytic transfusion reaction occurring as a result of ABO-mismatched platelets from group O donor with high-titer anti-A antibodies. SDP (in contrast to pooled platelets) offers the advantages of reduced risk of infection transmission and alloimmunization by limiting exposure to one donor only. However, it increases the opportunity for hemolytic transfusion reaction to occur if the donor has high-titer antibodies which would have been diluted if pooled platelets were used. As SDP use becomes more widespread, the risk of clinically significant hemolytic reactions is likely to increase, especially in seriously ill patients who tolerate these reactions particularly poorly. Moreover, increasingly, apheresis platelets are being donated by a small group of highly motivated donors, raising the chances of repeated transfusions from the same donors. We propose that the safety of ABO-mismatched platelet transfusions be re-evaluated. Effectiveness (and costs) of potential preventive strategies such as screening all SDP units for high-titer antibodies and/or plasma volume reduction of all mismatched SDP units should be studied.