Efficacy of pentastarch in granulocyte collection by centrifugal leukapheresis

The efficacy of 6% hydroxyethyl starch (hetastarch, HS) in enhancing granulocyte harvest by centrifugal leukapheresis has been described by a simple equation which predicts the granulocyte collection efficiency (GCE) based on an intrinsic donor variable, the erythrocyte sedimentation rate (ESR): GCE(%) = 1.3 ESR (mm/hr) + 45. Ten percent low molecular weight hydroxyethyl starch (pentastarch, PS) has been reported to be as effective as HS with potentially fewer adverse donor reactions (ADR). The derivation of an analogous equation for PS under conditions previously reported for HS may quantify PS efficacy and allow comparison to HS. We prospectively measured the in vitro and the in vivo effects of PS on the donor ESR in 53 granulocyte collections from 44 donors using the model CS-3000 Plus blood cell separator (CS). We then correlated the findings with the GCE of each procedure and derived an equation which expresses GCE in terms of baseline donor ESR. The in vitro addition of PS increased the donor ESR 2.4-fold, but its administration to a donor during a collection procedure did not appreciably change the ESR. Higher baseline donor ESR was more likely to result in more efficient cell collections: GCE (%) = 0.8 ESR (mm/hr) + 20; (r = 0.37). For granulocyte harvests using the CS and PS as the sedimenting agent 1) baseline donor ESR affects granulocyte harvests, but the poor correlation does not allow an accurate prediction of GCE and cell yield from the baseline donor ESR; 2) in comparison with HS (results from a previous study), PS may be less effective in vitro and not effective in vivo in elevating ESR, and may be less effective in enhancing granulocyte harvest; and 3) the parameters (slope, y-intercept, correlation coefficient) which define the linear relationship between baseline donor ESR and GCE may serve collectively as a quantitative measure of the effectiveness of different hydroxyethyl starch agents in enhancing granulocyte harvests. These parameters may be helpful in rapidly assessing the clinical efficacy of new, potentially useful hydroxyethyl starch agents prior to initiating a randomized, controlled clinical trial.