This animation demonstrates the actions of neutrophils in the acute inflammatory process. These series of events in the process of inflammation are mediated by:

  • Selectins: molecules on leukocytes (L-selectin) and endothelium (E-selectin, P-selectin) act as receptors to provide loose binding for rolling.

  • ICAM-1: intercellular adhesion molecule 1 provides more firm adhesion of the neutrophil, via integrins on neutrophil surfaces, to the endothelium.

  • CD31: this cell to cell adhesion molecule aids in diapedesis.

  • C5a and LTB4: chemotaxis is aided by the C5a component from complement activation, along with leukotriene B4, a product of the lipo-oxygenase pathway of arachidonic acid metabolism.

  • C3b and IgG: opsonins such as the C3b component from complement activation, as well as immunoglobulin G, coat foreign objects such as bacteria to aid in phagocytosis by binding to leukocyte receptors.

  • Myeloperoxidase, lysozyme: after engulfment, killing of bacteria occurs via generation of toxic oxygen species (superoxide) converted to hydrogen peroxide and further converted to a hypochlorous radical by myeloperoxidase from neutrophil granules. In the absence of oxidation, lysozyme from neutrophil granules can form holes in microbial membranes.