MBL-associated serine proteases (MASPs) and infectious diseases

Mol Immunol. 2015 Sep;67(1):85-100. doi: 10.1016/j.molimm.2015.03.245. Epub 2015 Apr 8.


The lectin pathway of the complement system has a pivotal role in the defense against infectious organisms. After binding of mannan-binding lectin (MBL), ficolins or collectin 11 to carbohydrates or acetylated residues on pathogen surfaces, dimers of MBL-associated serine proteases 1 and 2 (MASP-1 and MASP-2) activate a proteolytic cascade, which culminates in the formation of the membrane attack complex and pathogen lysis. Alternative splicing of the pre-mRNA encoding MASP-1 results in two other products, MASP-3 and MAp44, which regulate activation of the cascade. A similar mechanism allows the gene encoding MASP-2 to produce the truncated MAp19 protein. Polymorphisms in MASP1 and MASP2 genes are associated with protein serum levels and functional activity. Since the first report of a MASP deficiency in 2003, deficiencies in lectin pathway proteins have been associated with recurrent infections and several polymorphisms were associated with the susceptibility or protection to infectious diseases. In this review, we summarize the findings on the role of MASP polymorphisms and serum levels in bacterial, viral and protozoan infectious diseases.

Keywords: Complement system; MASP-1; MASP-2; MASP-3; MAp19; MAp44.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Bacterial Infections / genetics
  • Bacterial Infections / immunology*
  • Bacterial Infections / microbiology
  • Bacterial Infections / pathology
  • Complement Pathway, Mannose-Binding Lectin / genetics
  • Complement System Proteins / genetics
  • Complement System Proteins / immunology
  • Gene Expression Regulation / immunology
  • Humans
  • Mannose-Binding Lectin / genetics
  • Mannose-Binding Lectin / immunology
  • Mannose-Binding Protein-Associated Serine Proteases / genetics
  • Mannose-Binding Protein-Associated Serine Proteases / immunology*
  • Polymorphism, Genetic
  • Protozoan Infections / genetics
  • Protozoan Infections / immunology*
  • Protozoan Infections / parasitology
  • Protozoan Infections / pathology
  • Signal Transduction
  • Virus Diseases / genetics
  • Virus Diseases / immunology*
  • Virus Diseases / pathology
  • Virus Diseases / virology


  • Mannose-Binding Lectin
  • Complement System Proteins
  • MASP1 protein, human
  • MASP2 protein, human
  • Mannose-Binding Protein-Associated Serine Proteases