Flexible association of hemopoietic differentiation programs in multilineage colonies

Pluripotent hemopoietic progenitors lose potentialities during the process of differentiation. We have examined events that lead to lineage restriction by determining the cellular composition of 785 multilineage colonies grown from peripheral blood samples of glucose-6-phosphate-dehydrogenase (G-6-PD) heterozygous volunteers. Of these colonies, 762 contained only one isoenzyme type and were considered to be of clonal origin. A considerable heterogeneity was observed. Some colonies were composed of cells belonging to two different lineages, while other colonies contained three or more different cell types. A small number of colonies consisted--in addition to myeloid cells--of T-lymphocytes. The variable association within individual colonies of members belonging to different hemopoietic lineages suggests a flexible determination and expression of differentiation programs by early progenitors.