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. Author manuscript; available in PMC: 2017 May 2.
Published in final edited form as: Semin Immunol. 2016 Mar 25;28(2):109–118. doi: 10.1016/j.smim.2016.03.005

Table 1.

Expression sites, ligands and activities of soluble pattern recognition molecules.

Soluble pattern recognition molecules Expression sites Ligands Activities on innate immunity and neutrophil-dependent immunity
Collectins (MBL, SP-A, SP-D)

  • Liver (hepatocytes)

  • Lung (type II alveolar cells)

  • Carbohydrates and lipids exposed on pathogen surfaces (viral glycoprotein envelopes, LPS)

  • Opsonic activity of yeast

  • Increase of the activity of NETs to trap bacteria
Ficolins

  • M-ficolin: Myeloid cells (neutrophils, monocytes)

  • L-ficolin: Liver (hepatocytes)

  • H-ficolin: Liver and lung (type II alveolar cells)

  • Carbohydrates exposed on pathogen surfaces (GlcNAc, GalNAc)

  • Opsonic activity of fungi and bacteria

  • inhibition of viral infectivity and hemagglutination

  • found on neutrophil surfaces (activation of complement, cell polarization, aggregation and adhesion)
Properdin

  • Monocytes, macrophages, dendritic cells, mast cells, neutrophils

  • C3 convertase

  • Zymosan, bacteria (E. coli)

  • Amplification of the alternative complement activation pathway

  • Contribution in ANCA-mediated diseases
Long pentraxin PTX3

  • Myeloid cells (neutrophils, monocytes, macrophages, dendritic cells)

  • Epithelial cells

  • Endothelial cells

  • Fibroblasts

  • Adipocytes

  • Microorganisms (bacteria, fungi, viruses) and microbial moieties (OmpA)

  • Complement components (C1q, Factor H, C4BP, FHR-5)

  • P-selectin

  • M-ficolin, L-ficolin, MBL

  • Extracellular matrix protein (IαI, TSG-6, fibrin).

  • Fibrin, Plasminogen

  • Opsonic activity of fungi and bacteria

  • Activation and regulation of the complement system

  • Prevention of excessive neutrophil recruitment in tissues

  • Elimination of apoptotic cells

  • Target of autoantibodies

  • Matrix remodelling and fibrinolysis
Peptidoglycan-recognition proteins PGLYRP-1

  • Neutrophils

  • Eosinophils

  • Macrophages

  • Epithelial cells

  • Bacteria peptidoglycan

  • TREM-1

  • Bactericidal activity

  • Activation of TREM-1 expressing cells

Abbreviations: MBL, mannose-binding lectin; SP, surfactant protein; LPS, lipopolysaccharide; NETs, neutrophil-extracellular traps; GlcNAc, N-Acetylglucosamine; GalNAc, N-Acetylgalactosamine, ANCA, anti-neutrophil cytoplasmique antibody, Omp, Outer membrane protein; IαI, inter-α-trypsin inhibitor; TSG-6, TNF-α-induced protein 6; TREM, Triggering receptor expressed on myeloid cells