IMMUNOELECTRON MICROSCOPY ON EPOXY SECTIONS WITHOUT DEPLASTICIZING TODETECT GLOMERULAR IMMUNOGLOBULIN AND COMPLEMENT DEPOSITS IN RENAL DISEASES

Twenty renal biopsies were studied by immunoelectron microscopy (IEM) after embedding in epoxy resin. Immunogold labeling for immunoglobulin s and complement C3 was performed on the epoxy sections, which were no t subjected to any kind of etching or deplasticizing prior to the immu nolabeling. The concentration of accelerator, DMP-30 (Tri (Dimethyl Am ino Methyl) Phenol), was increased in the infiltration and embedding s teps far beyond the values normally used to make immunolabeling of the se antigens possible on epoxy sections. The sections were stained with tannic acid accompanied by uranyl acetate and lead citrate. Immunoflu orescence (IF) for light microscopy was carried out on frozen sections of parallel tissue samples. Some cases with IgA-nephritis demonstrate d a higher sensitivity for IEM than IF, in the sense that smaller amou nts of antigen were detectable with IEM. Ultrastructural preservation with this method was approximately the same as that usually seen on ep oxy-embedded material. By combining excellent immunolabeling with near ly optimal ultrastructural morphology in one procedure, this method is useful particularly in situations where the material available is lim ited, such as in studies of renal biopsies. As far as we know, this is the first time that immunoglobulins have been satisfactorily immunola beled on epoxy sections without etching or deplasticizing.