The Relationship between Complements and Age-Related Macular Degeneration and Its Pathogenesis

Figure 1

The classical pathway and the MBL pathway activate C1 and MBL-MASP-2, respectively, cleaving C2 and C4 to form C3 convertase. C4b2a combines with C3b formed after C3 cleavage to produce C5 convertase. In the alternative pathway, factor B combines with C3b, which is spontaneously hydrolyzed by C3 under the action of factors D and P to generate C3 convertase and C5 convertase. Both of the above enzymes can activate and cleave C5 and participate in the formation of the subsequent MAC.