Collectin-11/MASP complex formation triggers activation of the lectin complement pathway-the fifth lectin pathway initiation complex

YJ Ma, MO Skjoedt, P Garred - Journal of innate immunity, 2013 - karger.com
YJ Ma, MO Skjoedt, P Garred
Journal of innate immunity, 2013karger.com
Collectins and ficolins are important in the clearance of endogenous and exogenous danger
materials. A new human collectin-11 was recently identified in low concentration in serum in
complex with mannose-binding lectin (MBL)/ficolin-associated serine proteases. Collectin-
11 binds to carbohydrate residues present on various microorganisms. Thus, we
hypothesized that collectin-11 could be a novel initiation molecule in the lectin pathway of
complement. We can show that collectin-11 associates with all the known MBL-associated …
Abstract
Collectins and ficolins are important in the clearance of endogenous and exogenous danger materials. A new human collectin-11 was recently identified in low concentration in serum in complex with mannose-binding lectin (MBL)/ficolin-associated serine proteases. Collectin-11 binds to carbohydrate residues present on various microorganisms. Thus, we hypothesized that collectin-11 could be a novel initiation molecule in the lectin pathway of complement. We can show that collectin-11 associates with all the known MBL-associated serine proteases (MASP-1, MASP-2 and MASP-3) as well as the lectin complement pathway regulator MAP-1. Furthermore, we found that complex formation between recombinant collectin-11 and recombinant MASP-2 on Candida albicans leads to deposition of C4b. Native collectin-11 in serum mediated complement activation and deposition of C4b and C3b, and formation of the terminal complement complex on C. albicans. Moreover, spiking collectin-11-depleted serum, which did not mediate complement activation, with recombinant collectin-11 restored the complement activation capability. These results define collectin-11 as the fifth recognition molecule in the lectin complement pathway in addition to MBL, ficolin-1, ficolin-2 and ficolin-3.
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