Further evidence supporting an in vivo role for colony-stimulating factor.

Nude mice injected subcutaneously with CSF-producing human pancreatic carcinoma (MIA PaCa-2) cells developed tumors accompanied by a rise in serum CSF activity, granulocytosis, and expanded marrow granulocyte pools, the extent of all of which correlated with tumor size. The tumor origin of the CSF was demonstrated by neutralization with the specific antibody. Resection of the tumor resulted in restoration of normal granulocyte levels. These observations lend further support to an in vivo role for CSF in the regulation of granulopoiesis.