Effector Molecule Source Activity Target Organisms
Lysozyme 13 µg/mL in vaginal fluid, 1 mg/mL in mucus plug [92] Secreted by serous cells in submucosal glands [11]  Cleaves bonds in peptidoglycan component of cell walls, cationic disruption of microbial membranes [93] Gram-negative bacteria [93]
Weak at normal concentrations against bacteria, some antiviral (HIV) [94]
Lactoferrin
1 µg/mL in vaginal fluid, 100 µg/mL in cervical plug [92]
Secreted by serous cells in submucosal glands [11]* Sequesters iron, also disrupts microbial membranes [11]
Inhibits cellular fusion and entry by virus [95]
Gram negative bacteria [93] , virus [95]
Calprotectin
34 µg/mL [11]
Component of neutrophils, monocytes and keratinocytes [95] Sequesters zinc [11] Inhibits growth of fungi and yeast [96]
Human Alpha Defensins HPN 1,2,3,4 about 2 µg/mL [59] Synthesized in bone marrow [97] Comprise contents of phagocytic vacuoles that effect microbicidal activity [98]
increase the production of TNF and IL-1
Bacteria, fungi, viruses [11]
5 HD5
10 to 40 ng/mL
Columnar epithelium of endocervix [99] Binds electrostatically to negatively charged microbial particle, forming pores in cell membrane and eventually causing lysis [100] Bacteria, fungi, viruses [11]
Human Beta Defensins vaginal epithelial cells leukocytes [11]
HBD‑1 is produced constitutively in mucosa [11]
Human defensins HBD2 and 3 are induced at inflamed sites [11]    
Antimicrobial activity, inhibition of HIV-infectivity of immunocompetent cells, chemoattraction of T cells immature dendritic cells B cells neutrophils and macrophages [101,102] Gram-positive or Gram- negative bacteria, mycobacteria. yeast, enveloped viruses viral (in vitro) [103]
SLPI
10 to 100 µg/mL in vaginal secretions, as high as 1000 µg/mL in cervical mucus plug [11]    
Found in epithelial secretions, also produced by macrophages [11] Blocks action of hostile enzymes released by invading organisms [3]  Suppresses central transcription factor of inflammatory response [104] Bacteria and fungi  (weak at normal concentrations) [11]
 Antiviral (HIV-1) [61]
Surfactin Protein A In vaginal secretions [105, 106] Facilitates phagocytosis of microbes, increases chemotaxis, increases oxidative burst by phagocytes, modulates pro- inflammatory cytokine production by immune cells [105- 107] Bacteria, viruses [105, 106]
Surfactin Protein D In vaginal secretions [108] Increases permeability of bacterial cell membranes [107]
  stimulates oxygen radical release, contributing to destruction of virus [109]
Bacteria [107], viruses [108]
MBL Transudate from liver Facilitates complement activation and opsonization by binding to pathogenic microbes [63]  
Elafin Epithelial cells Antimicrobial , inhibits inflammation-related tissue damage by blocking elastase [3]  
Cathelicidin (LL-37)
1 µg/mL[11]
Components of neutrophils[11] Postcoital processing from hCAP18 precursor to functional form, targeting specifically microbes which may have been introduced by intercourse [110] Bacteria and fungi [11]
HBD= human beta defensin; hCAP-18 = human cationic antimicrobial protein; HD5 = human alpha defensin 5; HIV = human immunodeficiency virus; HPN = human alpha defensin; IL‑1 = Interleukin-1; MBL = mannose binding lectin; SLPI = secretory leukocyte protease inhibitor; TNF = tumor necrosis factor
Table 4: Defense Effector Molecules in Innate Immunity.