Fig. 1

Activation of the lectin pathway. The PRMs, MBL, ficolins (-1, -2 or -3), or collectins (-10, -11), complexed with MASP-1 or -2, bind to PAMPs or DAMPs on cell surfaces. Upon binding, pro-enzyme MASP-1 autoactivates and is converted to its active form, being able to activate MASP-2 and cleave the complement factor C2. MASP-2 subsequently cleaves C4. The activation of this pathway results in the formation of the membrane attack complex (MAC), opsonization, and chemoattraction of other immune cells and inflammation