Purification of human monocytes by continuous gradient sedimentation in ficoll.

A new method of obtaining purified human monocytes has been developed. The peripheral blood mononuclear leukocytes are isolated by centrifugation over Ficoll--Hypaque and then further purified by sedimentation over a linear 5--10% Ficoll density gradient. In ten experiments, the average purity obtained was 77.1% macrophages and the mean yield was 22.4% of the monocytes contained in the peripheral blood leukocytes. Viability of monocytes isolated by this technique exceeded 95%. The cells were phagocytic and responded to human migration inhibitory factor.