Granulocyte-macrophage colony stimulating factor (GM-CSF) is a cytokine that functions as a white blood cell growth factor. GM-CSF stimulates stem cells to produce granulocytes (neutrophils, eosinophils and basophils) and monocytes. In addition, it has additional activities on hematopoietic, as well as non-hematopoietic lineage cells. GM-CSF is used as a medication to stimulate the production of white blood cells and thus prevent neutropenia following chemotherapy. GM-CSF has also recently been evaluated in clinical trials for its potential as a vaccine adjuvant in HIV-infected patients. Increased levels of GM-CSF have been reported in the serum of some cancer patients, including patients with lung cancer and patients with acute myelogenous leukemia. GM-CSF has also been reported to be increased in the peripheral blood of bronchial asthma patients and in extracts of psoriatic scales.