Multivariate analysis of the factors associated with the yield and purity of human monocyte isolation by countercurrent centrifugal elutriation (CCE).

Substantial variability in the purity and yield of human monocytes following countercurrent centrifugal elutriation (CCE) has been reported for some time; the factors influencing this variability have not been rigorously studied in the past. Utilizing 50 normal donors, we examined several dozen preprocedural variables possibly influencing 174 separate CCE experiments, and we determined the impact of these variables on the yield and purity of monocytes obtained following cytapheresis and CCE. Donor age was not correlated with CCE monocyte yield or purity; male gender correlated with higher monocyte purity following CCE purification. The major correlates of the yield and purity of monocytes obtained by CCE were the numbers and concentration of monocytes found in the leukocyte population entered into the elutriator apparatus. Fifty-eight percent of all donors gave a very consistent yield of monocytes by CCE, with a standard error from the mean of less than 15% over the 3 years of this study. All donors consistently gave fractions with a high percentage of monocytes, with the standard error of the mean CCE monocyte purity being less than 5% over the duration of the study. Thus, while the purity of monocytes collected by CCE is highly reproducible, the yield of monocytes by this procedure is somewhat less so. These monocyte purification endpoints are affected by a number of preprocedural variables centering mainly around the percentage, concentration, and total numbers of monocytes in the cytapheresis cell population.