UNICELLULAR OR MULTICELLULAR ORIGIN OF HUMAN GRANULOCYTE-MACROPHAGE COLONIES INVITRO

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  • 1 January 1979
    • journal article
    • research article
    • Vol. 54  (6) , 1395-1399
Abstract
The assumption that human granulocyte-macrophage colonies have a unicellular origin and were true clones was tested directly. Cells from 7 females heterozygous for the common glucose-6-phosphate dehydrogenase (G-6-PD) gene (GdB) and the variant GdA were cultured in semisolid medium for granulocyte-macrophage colony growth and the enzyme type of individual colonies was determined. When the colony density was less than 20/dish, more than 95% of colonies had type A or type B G-6-PD, but not both. At colony densities > 30/dish, 15-75% of colonies had both enzyme types and therefore arose from more than 1 cell. These results were consistent with a unicellular origin for the colonies only when they are cultured at low densities. With increasing colony density, there was a greater frequency of colonies with both type A and type B activity, suggesting that accurate enumeration of committed stem cells could only be performed at low colony concentrations.