Epitopes binding mechanism

In tissues and cells there are four types of sites where an antibody can bind (Fig. 5.1), but only one is the correct site. Nonspecific binding occurs when an antibody binds by a mechanism other than by Fab-epitope binding. 

Nonspecific antibody binding - occurs when an antibody binds by a mechanism other than by epitope binding. 

Fig. 1. Transmission mechanisms. Strain barrier PrPc (circle) interacts with different strains of PrPSc (square or triangle). The replicated PrPSc is similar to the template. The 3F4 epitope is not recognized when it is in PrPSc, but is exposed after pardal denaturation by GdnHCI so that it is detected by the antibody. Antibody reactivity depends on the particular strain of PrP (Safar et aL, 1998). Species barrier when the template PrPSc contains unfavorable residues at the binding interface, the transformation of PrPc to Pr l>Sr does not occur. In vitro replication 35S label of PrPc is detected in PrPSc after replication in a medium containing GdnHCI (Kocisko et aL, 1994).

Once an antibody has egressed into the interstitial space, its movement is somewhat more complicated than simple diffusion around the interstitial space (until it binds to epitope) or flow into lymphatics for mononuclear phagocytic clearance. There are a number of mechanisms by which antibodies (that are not bound via CDR to target or a cross-reactive epitope) are transported across and to a variety of cell types. Below are discussed several specialized and/or tissue-specific mechanisms of IgG transport and/or clearance. 

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