Monocyte contamination in Ficoll-Hypaque mononuclear cell concentrates.

Monocyte contamination in mononuclear concentrates prepared by Ficoll-Hypaque (F-H) centrifugation was assessed by the following criteria: (a) morphology (Wright-Giemsa stain), (b) function (phagocytosis), and (c) cytochemical staining (non-specific esterase both manually and by flow cytophotometry). Studies on F-H preparations from blood samples obtained from 50 randomly selected patients irmined by functional and cytochemical staining. Monocyte counts determined by flow cytophotometric studies of cells stained in suspension for esterase were very similar to those based on phagocytosis and manual cytochemical staining technics. It is concluded that: (1) manual Wright-Giemsa staining alone is not adequate to accurately quantitate monocyte populations in F-H concentrates, and (2) cytochemical staining and flow cytophotometry can be used for rapid and accurate quantitation of monocyte contamination in F-H mononuclear concentrates.