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Front Immunol. 2012 Jul 16;3:205. doi: 10.3389/fimmu.2012.00205. eCollection 2012.

The salivary scavenger and agglutinin binds MBL and regulates the lectin pathway of complement in solution and on surfaces.

Author information

  • 1Infection Biology Research Program, Department of Bacteriology and Immunology, Haartman Institute, University of Helsinki, Helsinki, Finland.

Abstract

The salivary scavenger and agglutinin (SALSA), also known as gp340, salivary agglutinin and deleted in malignant brain tumor 1, is a 340-kDa glycoprotein expressed on mucosal surfaces and secreted into several body fluids. SALSA binds to a broad variety of microbes and endogenous ligands, such as complement factor C1q, surfactant proteins D and A, and IgA. Our search for novel ligands of SALSA by direct protein-interaction studies led to the identification of mannan-binding lectin (MBL) as a new binding partner. We observed that surface-associated SALSA activates complement via binding of MBL. On the other hand, soluble SALSA was found to inhibit Candida albicans-induced complement activation. Thus, SALSA has a dual complement activation modifying function. It activates the lectin pathway when bound to a surface and inhibits it when free in the fluid phase. These activities are mediated via a direct interaction with MBL. This suggests that SALSA could target the innate immune responses to certain microorganisms and simultaneously limit complement activation in the fluid phase.

KEYWORDS:

complement regulation; gp340; lectin pathway; mannan-binding lectin; mucosal immunity; salivary agglutinin; scavenger receptor cysteine-rich

PMID:
22811680
[PubMed]
PMCID:
PMC3397308
Free PMC Article
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