GM-CSF has a key role in enhancing the antimicrobial activities of neutrophils and macrophages by augmenting the expression of CD11b, an adhesion molecule that mediates neutrophil adhesion to endothelial cells, and hence promoting the recruitment of neutrophils to the site of infection; promoting the differentiation of macrophages and dendritic cells (DCs); and by priming the phagocytosis and bactericidal activities of these cells. The gene discussed is CSF2; the disease is infection.