Innate Immunity Antibodies


Characterization, markers and antibodies

Neutrophils are the most abundant leukocyte found in the human blood stream and form the vanguard of the body’s cellular immune response. They develop in the bone marrow from granulocyte monocyte precursor (GMP) haematopoietic stem cells under the control of granulocyte colony-stimulating factor (G-CSF) in a process known as granulopoiesis, before being released into the blood stream. Circulating neutrophils are short lived (approximately five hours) but recruitment to sites of injury and/or infection can increase their lifespan significantly to several days. The capture of neutrophils from the blood stream occurs at sites of inflammatory-activated endothelium, where the neutrophil engages with endothelial selectins, leading to rolling, before firmly adhering to the vascular wall via integrins and transmigrating to the tissue beneath (Vestweber, 2007). This process is one of the mechanisms by which neutrophils are “primed” in readiness for activation (other mechanisms include exposure to early markers of inflammation including TNF-alpha and Interleukin 1-alpha) (Condliffe et al. 1998). Using an array of cell surface receptors, the extravasated neutrophil is able to travel through the tissue by chemotaxis, following chemokine and/or pathogen-derived molecule concentration gradients to the site of injury (Griffith et al. 2014).

Exposure to higher levels of inflammatory mediating molecules and/or pathogen derived molecules leads to activation of the neutrophil (Kolaczkowska and Kubes 2013), when the cell becomes able to attack microbes by a variety of mechanisms. Firstly, neutrophils can recognize pathogens directly through pattern recognition receptors, or engage them by Fc or complement receptors to opsonized targets. The pathogen is then phagocytosed, where fusion with granules containing anti-microbial molecules and the generation of reactive oxygen species results in its destruction. A second mechanism of microbe attack is degranulation, when granules discharge their contents directly into the milieu. The three types of granules were historically known as azurophilic or primary, specific or secondary, and gelatinase or tertiary, however it is now postulated that the different granule types are all part of a single continuum (Borregaard and Cowland 1997). The anti-microbial contents of these granules include myeloperoxidase, defensins, cathepsins, lysozyme, gelatinases and serine proteases. Finally, activated cells may produce neutrophil extracellular traps (NETs). Nuclear swelling together with degranulation leads to the expulsion from the cell of DNA strands, forming a web with attached anti-microbial proteins. This mesh serves to both immobilize and destroy pathogens (Brinkmann et al. 2004).

Neutrophils can be identified by the expression of certain markers, refer to the table below. To view antibodies available to these markers simply click on the marker.

Human Markers

Mice Markers























Defensin (alpha 1, beta 1,2,3)







  • Borregaard N and Cowland JB. (1997). Granules of the human neutrophilic polymorphonuclear leukocyte. Blood. 89, 3503-3521.
  • Brinkmann V et al. (2004). Neutrophil extracellular traps kill bacteria. Science. 303, 1532-1535.
  • Condliffe AM et al. (1998). Neutrophil priming: pathophysiological consequences and underlying mechanisms. Clin. Sci. (Lond). 94, 461-471.
  • Griffith JW et al. (2014). Chemokines and chemokine receptors: positioning cells for host defence and immunity. Ann. Rev. Immunol. 32, 659-702.
  • Kolaczkowska E and Kubes P. (2013). Neutrophil recruitment and function in health and inflammation. Nat. Rev. Immunol. 13, 159-175.
  • Vestweber D. (2007). Adhesion and signaling molecules controlling the transmigration of leukocytes through endothelium. Immunol. Rev. 218, 178-196.