Clonal analysis of progenitor cell commitment to granulocyte or macrophage production

Abstract

Granulocyte‐macrophage colony formation by C57BL bone marrow cells was initiated in agar cultures either by the granulocyte‐macrophage stimulus, GM‐CSF, or by the predominantly macrophage stimulus, M‐CSF. After 24 hours, paired daughter cells of granulocyte‐macrophage colony‐forming cells (GM‐CFC) were separated by micromanipulation and one cultured in GM‐CSF, the other in M‐CSF. From the differentiation pattern of the resulting colonies, irreversible commitment of some cells occurred during the first 24 hours and completion of the first cell division. A similar result was obtained using granddaughter cells present after 24 hours of incubation. However, when intact developing day 2 and days ..