Transgenic mice as models of hemopoiesis

A useful approach to establishing the biologic actions, in vivo, of granulocyte-macrophage colony-stimulating factor (GM-CSF) is to assess the consequences of long-term elevation of the factor in transgenic mice. Two lines of transgenic GM-CSF mice were analyzed. The major abnormality exhibited was an elevation in the number of macrophages, eosinophils, and polymorphs in the peritoneal and pleural cavities. Disease states exhibited by the lines were dependent on the insertion site of the GM-CSF gene. These disease states seem best explained on the basis of CSF-mediated macrophage activation and may provide valuable clues as to the cause of comparable human diseases such as malignant histiocytosis, polymyositis, or rheumatoid arthritis.