Table 1.
Antimicrobial products of human phagocytes that are delivered to phagosomes
| Product | Neutrophils* | Macrophages† |
|---|---|---|
| ROI | + | + |
| RNI | + | + |
| Myeloperoxidase | + | − |
| Lactoferrin | + | − |
| Bacterial permeability increasing factor | + | − |
| Serprocidins (elastase, cathepsin G, protease 3, azurocidin) | + | − |
| Phospholipase A2 | + | − |
| Cathelicidin | + | − |
| Lysozyme | + | − |
| Defensins (HNPs) 1, 2, 3, 4 | + | − |
Proteins with antimicrobial activity that are predominantly nuclear, cytosolic, or secreted are not listed. Moreover, depletion of (micro)nutrients from phagosomes may be an important antimicrobial mechanism. For example, down-regulation of transferrin receptors can starve the pathogen for iron, and Nramp1 is a phagosomal membrane protein that may transport iron.
*
Antibacterial proteins specific to eosinophils are not included.
†
Monocytes contain some of the antimicrobial proteins of neutrophils until they differentiate into macrophages.