Stimulated granulocytopoiesis in mice bearing fibrosarcoma

Bone marrow, spleen and blood from (CBAT6T6 × C57BL)F1 mice bearing transplantable fibrosarcoma contained more CFUs than the same tissues from normal mice. In all the tissues assayed the pool of CFUs that form myeloid colonies in the spleen of recipient mice was particularly enlarged. Marked granulocytosis, corresponding to a stimulated granulocytopoiesis, indicated an increased release of differentiated cells into peripheral blood. Fibrosarcoma also decreased the immunological reactivity of host's spleen toward allogeneic tissue. These effects are explained in terms of a granulocytopoiesis-promoting factor secreted by the tumour, by “consumption” of granulocytes in the tumour, or by antigenicity of the tumour.