Antibody, effector functions

Immunoglobulins are glycoproteins. The carbohydrate moiety is attached to the heavy chain (usually the Ch2 domain) via an N-linked glycosidic bond. Removal of the carbohydrate group has no effect upon antigen binding but does affect various antibody effector functions and alters its serum half-life. 

Hodoniczky J, Zheng YZ, James DC. Control of recombinant monoclonal antibody effector functions by Fc N-glycan remodeling in vitro. BiotechnolProg 2005 21 1644-1652. 

Another effector function is the cell-mediated cytotoxicity. Infected cells that were recognized and opsonized by specific antibodies can be lysed by natural killer cells which are the classical K cells. These properties are highly determined by the Fc part of antibodies. IgGl and IgG3 have the highest capacity for cell-mediated cytotoxicity. The effector function of an antibody is frequently used as a mean of antibody recognition. This is especially the case with bacterial proteins such as protein A and protein G that specifically interact with the same domain. Therefore purification can interfere with the antibody effector function. 

The residues not in the framework region form the loops between the p strands. These loops may vary in length and sequence among immunoglobulin chains of different classes but are constant within each class the sequence of the loops is invariant. The functions of these loops are not known, but they are probably involved in the effector functions of antibodies. When an antibody-antigen complex has been formed, signals are... 

T-c fl effector functions Antibody response T-cell effector functions... 

Administration of Tyv-specific monoclonal antibodies to rat pups already infected with intestinal larvae causes larvae in the epithelium to be expelled (Carlisle et al, 1990). Only the LI stage is susceptible to expulsion once the larva has moulted to L2 it resists the effects of the antibodies (Carlisle et al, 1990). Expulsive immunity is transferred by three IgG isotypes, F(ab )2 fragments, as well as IgM (Carlisle et al., 1991a). These findings argue against a role for Fc-mediated effector functions and imply that antibodies against Tyv can disturb the larva s niche in a direct fashion. 

Scallon, BJ. et al., Chimericanti- TNF-a monoclonal antibody cA2 binds recombinant transmembrane TNF-a and activates immune effector functions, Cytokine, 7, 251,1995. 

Fc fragment (for Fragment, crystallizable) A region of an antibody (IgG molecule) composed of two heavy chains on the C-terminal side. Fc has many effector functions (e.g., binding complement, binding to cell receptors on macrophages and monocytes, etc.) and serves to distinguish one class of antibody from another. 

---