Mannose-binding lectin (MBL)-associated serine protease (MASP)-1 contributes to activation of the lectin complement pathway

Minoru Takahashi, Daisuke Iwaki, Kazuko Kanno, Yumi Ishida, Jie Xiong, Misao Matsushita, Yuichi Endo, Shigeto Miura, Naoto Ishii, Kazuo Sugamura, Teizo Fujita

Research output: Contribution to journalArticlepeer-review

132 Citations (Scopus)


The complement system plays an important role in innate immunity. In the lectin complement pathway, mannose-binding lectin (MBL) and ficolins act as recognition molecules, and MBL-associated serine protease (MASP) is a key enzyme. It has been suggested that MASP-2 is responsible for the activation of C4. Other serine proteases (MASP-1 and MASP-3) are also associated with MBL or ficolins; however, their functions are still controversial. In this study, a MASP-1- and MASP-3-deficient mouse model (MASP1/3-/-) was generated by a gene targeting strategy to investigate the roles of MASP-1 and MASP-3 in the lectin pathway. Serum derived from MASP1/3-/- mice showed significantly lower activity of both C4 and C3 deposition on mannan-agarose, and this low activity was restored by the addition of recombinant MASP-1. MASP-1/3-deficient serum showed a significant delay for activation of MASP-2 compared with normal serum. Reconstitution of recombinant MASP-1 in MASP-1/3-deficient serum was able to promote the activation of MASP-2. From these results, we propose that MASP-1 contributes to the activation of the lectin pathway, probably through the activation of MASP-2.

Original languageEnglish
Pages (from-to)6132-6138
Number of pages7
JournalJournal of Immunology
Issue number9
Publication statusPublished - 2008 May 1
Externally publishedYes

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology


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