Mouse Models and Tools for the in vivo Study of Neutrophils (1)
Neutrophils can release Neutrophil Extracellular Traps (NETs), which are composed of DNA decorated with proteins such as cathepsins, histones, neutrophil elastase and myeloperoxidase (MPO). NETs are sticky weblike structures, which are thought to trap pathogens and toxins, thereby inactivating them and preventing them from spreading.
Depleting Antibodies
Anti-Gr-1: The monoclonal rat IgG2b antibody RB6-8C5 was originally reported to specifically bind to neutrophils, and recognize the surface molecule Gr-1. C3-deficient mice were shown to exert no depletion upon RB6-8C5 treatment, indicating that opsonization of neutrophils is a prerequisite for their depletion. Injection of RB6-8C5 antibody in TNF-α pre-treated mice induces death due to microvessel obstruction and coagulation resulting in respiratory defects. This is thought to be a consequence of neutrophil activation following binding of RB6-8C5 antibodies to TNF-α-primed cells.
Anti-Ly6G: The rat IgG2a antibody 1A8 has been described as being specific for Ly6G, and therefore as interacting specifically with neutrophils. 2 days post-treatment, neutrophil counts rise again in 1A8-treated mice while it is not the case in RB6-8C5-treated mice. 1A8 antibody has been extensively used to study the contribution of neutrophils in vivo, such as neutrophils supporting metastasis formation. NIMP-R14 is a second monoclonal antibody reported to recognize Ly6G. NIMP-R14 treatment leads to >95% depletion of spleen and blood neutrophils. Neutrophil counts return to basal levels about 3 days post- NIMP-R14 injection.
NETosis is an innate immune mechanism that involves the release of DNA decorated with histones and granule enzymes upon neutrophil activation.