Guide to Multiple Labeling with Secondary Antibodies

Fab fragment antibodies are generated by papain digestion of whole IgG antibodies to remove the entire Fc portion, including the hinge region. Block endogenous immunoglobulins on cells, tissues , or other surfaces. Block exposed immunoglobulins in multiple labeling experiments using primary antibodies from the same species. Fab-label primary antibodies in solution without compromising activity.

F(ab')2 fragments of antibodies are generated by pepsin digestion of whole IgG antibodies to remove most of the Fc region while leaving intact some of the hinge region. Used for specific applications, such as to avoid binding of antibodies to live cells with Fc receptors or to Protein A or Protein G. 

Whole IgG antibodies are isolated as intact molecules from antisera by affinity chromatography.