CLONAL ANALYSIS OF THE ACTION OF GM-CSF ON THE PROLIFERATION AND DIFFERENTIATION OF MYELOMONOCYTIC LEUKEMIC-CELLS

With 214 subclones of the BALB/c myelomonocytic leukemia WEHI‐3B, the granulocyte‐macrophage colony‐stimulating factor (GM‐CSF) in impure or purified form, consistently increased the proportion of colonies exhibiting partial or complete differentiation in agar cultures. GM‐CSF also increased colony size and content of daughter colony‐forming cells. Serial recloning of WEHI‐3B colonies in the presence of GM‐CSF showed that when colonies differentiated completely, self‐replication of the colony‐forming cell was suppressed (clonal extinction). However, WEHI‐3B cells exhibited clonal instability and even in the continuous presence of GM‐CSF many colony‐forming cells still generated cells able to form undifferentiated colonies. It appears unlikely that GM‐CSF can completely suppress the progressive proliferation of a myeloid leukemic population of the WEHI‐3B type. Copyright © 1979 Wiley‐Liss, Inc., A Wiley Company