Table 1

Structure, anti-microbial and immunomodulatory activities of innate immunity proteins and peptides
Protein	Structure	pI	Pulmonary Source	Antimicrobial activity	Immunomodulatory activity

Lactoferrin	Iron- binding glycoprotein MW 80 kDa	8.7	Neutrophil secondary specific granules and submucosal gland epithelial cells	Bactericidal Bacteriostatic Inhibits biofilm formation Anti-fungal Anti-viral	Binds LPS and can prevent septic shock. Binds CPG motifs. Anti-oxidant.
SLPI	11.7 kDA non-glcosylated protein	>9.2	Macrophages, epithelial cells, neutrophils	Bactericidal Bacteriostatic Anti-viral	Powerful anti-protease Inhibits LPS-induced NF-κB activation. Attenuates pulmonary recruitment of neutrophils in sepsis models. Impairs LTA and LPS induced proinflammatory gene expression in monocytes and macrophages.
Lysozyme	14 kDA enzyme	10.5	Neutrophil secondary specific granules and submucosal gland epithelial cells	Bactericidal Bacteriostatic	Unknown
Human Defensins	3–5 kDA peptides	8.8–9.5	Neutrophil azurophil granules and pulmonary epithelial cells	Bactericidal Bacteriostatic Anti-parasitic Anti-fungal Anti-viral	Mitogenic and chemotactic activities. Contribute to epithelial repair in the lung by enhancing epithelial cell proliferation.
LL-37	Peptide that requires proteolytic processing to liberate the mature functional antimicrobial peptide.		Neutrophil secondary specific granules and submucosal gland epithelial cells	Bactericidal Bacteriostatic Anti-fungal Anti-viral	Reduced production of the pro-inflammatory cytokine TNF-α from macrophages stimulated with LPS and may be responsible for the migration of immune cells to areas of inflammation and infection
BPI	55-kDa protein	9.6	Neutrophil primary granules	Bactericidal Bacteriostatic Act as an opsonin to enhance neutrophil phagocytosis.	Downregulates LPS and other endotoxins in vivo
Surfactant proteins A and D	Lipoprotein complex	4.5–5.4	Type II pneumocytes, airway Clara cells	Key opsonins facilitating phagocytosis of bactaeria and viruses. Bactericidal Bacteriostatic Anti-fungal Anti-viral	Both SP-A and SP-D have the capacity to modulate multiple leucocyte functions
Lactoperoxidase	Enzyme		Airway epithelium	Bactericidal Anti-fungal Anti-viral
CCL20	Chemokine with similar structure to HBD		Airway epithelium	Bactericidal against Gram negative bacteria	Stimulates the migration of B-cells, immature dendritic cells, and a subset of memory T cells

Rogan et al. Respiratory Research 2006 7:29 doi:10.1186/1465-9921-7-29