Granulocyte-macrophage precursor cell responses in mice of different strain, sex and age.

Mice inoculated with Freund's complete adjuvant show an increase in the number of granulocyte-macrophage precursor cells (colony-forming cells) in haemopoietic tissues. This effect is most marked in spleen and reaches a maximum 7 days after inoculation. The magnitude of the cellular response was measured in five mouse strains (C57B1, CBA, VSBS, TO and HR) and some significant differences were found, although no differences in the level of serum regulating factors were apparent. Colony-forming cell responses were weaker in young adult males than in females and were also weaker in mice at extremes of age. It was suggested that differences in the magnitude of cellular responses could reflect differences in the responsiveness of target cells to the same stimulus and that broad parallels may exist between myelopoietic and immunological responsiveness.