Assay for Chemoattractant Binding

Phagocytic leukocytes play a major role in host defense because they rapidly migrate to sites of infection and destroy invading microorganisms. Specific signal molecules (chemoattractants), released by bacteria or endogenously generated by the host, can elicit directed leukocyte migration (chemotaxis) to the inflammatory site. Chemotaxis is initiated by the specific interaction (binding) of chemoattractants with leukocyte plasma membrane receptors. Polymorphonuclear leukocytes (neutrophils) migrate to a variety of chemoattractants, including N-formyl peptides, complement-derived C5a, leukotriene B⁴ , interleukin-8, and platelet-activating factor, each of which has a distinct receptor on the leukocyte plasma membrane.