Activation of lectin pathway begins when mannan-binding lectin (MBL, also called mannose-binding protein, MBP) or ficolins bind to cell-surface carbohydrates on the target cell in the presence of Ca2+. Surface bound lectins are assembled with MBL-associated serine proteases (MASPs) [Turner MW et al 1996, Fujita T et al 2004]. The lectin-MASP complex cleaves C4 and C2 complements to generate their active fragments. The active fragments - C4b and C2b, form C3 convertase [Wallis R et al 2007].
Most of the components of chicken lectin pathway (MBL, ficolin, MASP2, MASP3, MAp19) have been mapped, cloned and characterized (Laursen SB and Nielsen OL 2000; Lynch NJ et al 2005).