Preparation of ferritin conjugates and antibodies for the localization and identification of antigens in tissues and cells by electron microscopy.

Ferritin, due to its high electron density, serves s a good marker in immunoelectron microscopic studies to localize antigens on and in cells and tissues. A step-by-step methodology for the conjugation of antibodies to ferritin is presented. Special attention has been placed on the techniques for the purification of ferritin and antibodies, conjugation procedures, and the treatment of specimens with conjugates. Methods for obtaining the separation of conjugated antibodies from unconjugated antibodies and for testing the purity and specificity of the labeling reagents are discussed.