The lectin pathway (LP) is activated when either mannose binding lectin (MBL) or Ficolin bind to carbohydrate moieties on surfaces of pathogens including yeast, bacteria, parasites and viruses. Both MBL and Ficolin circulate in the serum as complexes with MBL-associated proteins (MASPs; Wallis 2007; Sørensen et al. 2005) . There are four structurally related MASPs: 1, 2 and 3 and a truncated MASP2 known as MAP19 (Sørensen et al. 2005) . Binding to pathogens induces conformational changes resulting in autoactivation of MASP2 which cleaves C4 to form C4a and C4b. C4b attaches to the surface of the pathogens inducing C2 to bind, which is in turn cleaved by MASP2 to form C2b and C2a. C4b together with the attached C2a has enzymatic activity and forms the LP C3 convertase C4bC2a. The exact role of the other MASPs is presently unknown although MASP1 can cleave C2 but not C4 (Wallis 2007) and thus help in enhancing complement activation by the bound complexes.