Blocking and Permeability.

There are two key elements in immunocytochemistry: (1) to allow binding of the antibodies only to appropriate sites and (2) to allow antibodies access to antigens inside cells. Antibodies are proteins and can bind to tissue in ways other than specific via Fab binding. If the antibodies bind nonspecifically, then the labeling will occur as if the antibodies were bound to an antigen. Blocking of these nonspecific sites is an important and necessary step. A second requirement is that tissues and cells must be treated to allow antibodies to get inside the membranes to the cytoplasm. This is called permeabilization of cells and is done with detergents. [ABSTRACT FROM AUTHOR]