Effect of resin use in the post-embedding procedure on immunoelectron microscopy of membranous antigens, with special reference to sensitivity.

To investigate quantitatively the effect of resins on the sensitivity of immunoelectron microscopy of membranous antigen, ultra-thin sections of bovine epithelial tissue embedded in five different kinds of resins [JB-4 (JB4), LR Gold (LRG), Lowicryl K4M (K4M), Quetol 812 (Q812), and Spurr's (Spurr) resin] were labeled specifically with anti-desmosomal glycoprotein I(DGI) antibody followed by protein A-gold (PAG) conjugates. When we compared the labeling intensity expressed as the number of PAG particles per 500-nm length of the desmosomal region along the membrane, three hydrophilic resins (JB4, LRG, and K4M) showed much greater levels of labeling intensity than did epoxy resins (Q812 and Spurr), which had a negative value. The three hydrophilic resins showed only minor differences in their levels of labeling intensity. The intensity obtained with JB4, which was the highest of the three, was further increased by pretreatment of the ultra-thin sections with methyl methacrylate monomer (MM) for 5 min. On the basis of these results, wide applicability of this new technique for membranous antigens, which have been difficult to detect positively by any previously employed techniques, is suggested.