Hematopoietic Cell Yield Declines Predictably Over Time During Apheresis

s / Biol Blood Marrow Transplant 19 (2013) S178eS193 S183 days vs. 13.1 days, P 2 days of collection (n1⁄4279) to give individual log-HCMI decay curves. A quadratic equation (y1⁄4ax+bx+c) provided the best fit for these curves (mean R2 0.88), demonstrating a parabolic relationship such that log HCMI increased and declined in proportion to square of time (in days) following the start of apheresis. It was noted that the values of coefficients were normally distributed in the study population; coefficient a (mean, -0.04 0.2), b (0.04 1.1), and c (1.7 1.2). A Twostep cluster analysis of these coefficients distinguished three main groups (clusters) of patients. Patients in cluster 1 (38%) tended to have an initial increase in HCMI followed by an asymptotic decline; those in clusters 2 (50.2%) and 3 (8.6%) displayed declines of varying magnitude. Cluster 1 showed a higher proportion of NHL patients (p1⁄40.01), whereas MM was over-represented in cluster 2 (p1⁄40.008), consistent with the notion that prior chemotherapy received by NHL patients impacted their mobilization kinetics. In conclusion, we demonstrate that HC yield during various mobilization procedures follows mathematically predictable kinetics which may reflect underlying hematopoietic reserve.