Separation of human blood monocytes and lymphocytes on a continuous Percoll gradient

A method for separation of human blood monocytes and lymphocytes is described. Mononuclear leukocytes are centrifuged on a continuous gradient of colloidal silica particles (Percoll) in phosphate-buffered saline. This leads to formation of 4 bands: a layer containing dead material (if present) which did not enter the gradient; a layer near the bottom of the tube containing granulocytes and red cells, and two other bands in between. The upper one is enriched for monocytes (av. 78%) and the lower one for lymphocytes (av. 98%). The final yields of these cell types are 73% and 79%, respectively, and their viability is greater than 95%. No functional impairments could be detected by different criteria including the ability of B lymphocytes to produce immunoglobulins when stimulated with pokeweed mitogen and the ability of monocytes to phagocytize opsonized red cells and latex particles.