INVITRO REGULATION OF GRANULOPOIESIS IN HUMAN LEUKEMIA - APPLICATION OF AN ASSAY FOR COLONY-INHIBITING CELLS

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  • 1 January 1976
    • journal article
    • research article
    • Vol. 47  (3) , 389-402
Abstract
Two assays are described to detect the action of colony-inhibiting cells. In the 1st assay, a simple density separation technique was used to remove dense neutrophils (PMN) from suspensions of blood and of bone marrow cells prior to culture in semisolid agar. Conditions were arranged to ensure that control suspensions of unseparated cells and test suspensions of buoyant mononuclear cells differed only in their content of neutrophils. The control and test suspensions contained equal numbers of mononuclear cells (and granulocyte precursors). Colony (and cluster) formation was invariably enhanced in neutrophil-depleted cultures of normal cells. In the 2nd assay, dense PMN, treated by an adherence separation procedure, were recovered, and the nonadherent dense PMN were added back to PMN-depleted cultures. A reproducible dose-related decrease in colony (and cluster) formation to basal levels resulted. The inhibitory effect was identical when the PMN were added directly to the culture (overlayer) or to the underlayer. In PMN-depleted cultures obtained from patients with leukemia and other hemopoietic disorders, neither colony nor cluster formation was enhanced, and sometimes it was reduced. The effect of adding patient and normal nonadherent PMN to target cultures of normal and patient PMN-depleted cells were compared and some leukemic PMN were noninhibitory. Abnormalities of cellular interactions in vitro detected in the 1st assay may have more than 1 explanation, as shown when they are subjected to the closer scrutiny possible with the 2nd assay.

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