Lectins antibody activity

The reactions that take place in the complement system can be initiated in several ways. During the early phase of infection, lipopoly-saccharides and other structures on the surface of the pathogens trigger the alternative pathway (right). If antibodies against the pathogens become available later, the antigen-antibody complexes formed activate the classic pathway (left). Acute-phase proteins (see p. 276) are also able to start the complement cascade lectin pathway, not shown). 

Active targeting is used to describe the specific liposomal drug localization achieved by grafting various moieties (antibodies, lectins, polymers, etc.) on the carrier surface. 

The classical complement pathway reqnires activation by circulating antibodies, IgM or IgG (specific immnne response), while the alternative and lectin pathways can be activated in the absence of antibody (non-specific immnne response). 

Figure 15.1 Complement activation pathways. The classical, lectin and alternative pathways converge into a final common pathway when C3 convertase (C3 con) cleaves C3 into C3a and C3b. Ab = antibody, Ag = antigen, Cl-INH = Cl inhibitor, MAC = membrane attack complex, MASP = MBL-associated serine protease, MBL = mannose-binding lectin, P = properdin. Overbar indicates activation.

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