Separation of human lymphocytes and monocytes by velocity sedimentation at unit gravity

An improved method of separating human peripheral blood lymphocytes and monocytes by velocity sedimentation at unit gravity is described. Cell separation capacity is considerably increased, while the time required for optimal separation is markedly reduced. Simple devices make it possible to layer and fractionate the gradients within 15 min. Overall recovery is 85%. On a small scale, monocytes were isolated > 80% pure from 4–20 × 10 7 mononuclear leukocytes. The average yield was 40% of all monocytes recovered after fractionation. In the same sedimentation runs 60% of all recovered lymphocytes were obtained strongly depleted of monocytes (monocyte contamination < 0.2%). On a large scale 3–6 × 10 8 monocytes with an average purity of 85% were isolated from 3–6 × 10 9 mononuclear leukocytes in 2 subsequent runs. All cells recovered from the gradient were functionally active according to rosette formation, phagocytosis, stimulation by mitogens and in cytotoxicity tests.