Springer Seminars in Immunopathology

, Volume 27, Issue 3, pp 299–319

Mannan-binding-lectin-associated serine proteases, characteristics and disease associations

  • Rikke Sørensen
  • Steffen Thiel
  • Jens C. Jensenius
Original Article

DOI: 10.1007/s00281-005-0006-z

Cite this article as:
Sørensen, R., Thiel, S. & Jensenius, J.C. Springer Semin Immun (2005) 27: 299. doi:10.1007/s00281-005-0006-z

Abstract

Mannan-binding lectin (MBL)-associated serine proteases (MASPs) circulate in plasma as zymogens in complexes with MBL and with L- and H-ficolin. Upon binding of MBL or ficolin to pathogen-associated molecular patterns, the MASPs are activated. MASP-2 can now cleave C4 and C2 to generate the C3 convertase, C4bC2b. The functions of the other two MASPs, MASP-1 and MASP-3 have not been elucidated. MASP-1 can cleave C2, and with low efficiency also C3, and may serve a function through direct C3 activation. No natural substrate for MASP-3 has been identified. MBL deficiency, occurring at a frequency of about 10%, is the most common congenital immunodeficiency and is associated with susceptibility to infections and autoimmune disorders. Inherited MASP-2 deficiency has been described as the result of a mutation causing the exchange of aspartic acid with a glycine at position 105, a position in the first domain, CUB1, involved in calcium binding. This mutation abolishes the binding to MBL and ficolins, and deprives MASP-2 of functional activity. The index case suffered from recurrent severe infections and autoimmune reactions. The gene frequency of the mutation among Caucasians is 3.6%. It is not found in Chinese, who present a different mutation also associated with MASP-2 deficiency.

Copyright information

© Springer-Verlag 2005

Authors and Affiliations

  • Rikke Sørensen
    • 1
  • Steffen Thiel
    • 1
  • Jens C. Jensenius
    • 1
  1. 1.Department of Medical Microbiology and Immunology, Wilhelm Meyers AlléUniversity of AarhusAarhusDenmark

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