Coloidal gold, ferritin and peroxidase as markers for electron microscopic double labeling lectin techniques.

Three markers, colloidal gold, ferritin and peroxidase, were checked for usefulness in double labeling of lectin-binding sites. The amount of various lectins for the stabilization of good sols of a different particle size was evaluated. Several lectin-gold complexes were prepared for electron microscopic labeling purposes, and the optimal amount of various lectins needed for stabilization of gold solutions of a different particle size was determined. The following combinations were investigated for their usefulness in labeling two different lectin-binding sites: lectin-gold and lectin-gold (different particle size), lectin-gold and lectin-ferritin, as well as lectin-ferritin and lectin-peroxidase. Of these combinations the latter did not give satisfactory results for double labeling. In all single and double labeling techniques with the above mentioned markers the quantitative evaluation of the number of lectin-binding sites is not feasible, but these techniques will be of considerable value for the investigation of the dynamics of different lectin-binding sites on the cell surface.