Purity ~95% (SDS-PAGE). Macrophage Inflammatory Protein-1 is a factor produced by macrophages that causes local inflammatory responses, and induces superoxide production by neutrophils. Two peptides are responsible for this activity. They have been termed MIP-1-alpha, and MIP-1-beta. The two MIP proteins are the major factors produced by macrophages following their stimulation with bacterial endotoxins. Both proteins are involved in the cell activation of human granulocytes (neutrophils, eosinophils, and basophils) and appear to be involved in acute neutrophilic inflammation. Both forms of MIP-1 stimulate the production of reactive oxygen species in neutrophils and the release of lysosomal enzymes. They also induce the synthesis of other pro-inflammatory cytokines such as IL-1, IL-6 and TNF in fibroblasts and macrophages. MIP-1-alpha is a potent agonist of basophils, inducing a rapid change of cytosolic free calcium (see also: Calcium ionophore), the release of histamine and sulfido- leukotrienes, and chemota