The combination of high-accelerator epoxy resin and antigen retrieval to obtain more intense immunolabeling on epoxy sections than on LR-white sections for large proteins.

The purpose of this study was to examine how antigen retrieval affected the yield of immunogold labeling on epoxy sections based on embedding with different amounts of accelerator. The concentration of accelerator DMP-30 (tri(dimethyl amino methyl) phenol) was varied in the range of 0-8% in the processing of the tissue for epoxy embedding. Immunogold labeling was performed on epoxy sections and LR-White sections of fibrin clots and renal tissue with IgG-deposits, and the antibodies used were anti-fibrinogen anti-IgG and, respectively. For some of the sections antigen retrieval was performed by heating the sections in citrate buffer. In all cases, the yield of immunogold labeling increased following antigen retrieval. The increase (%) in the yield of immunogold labeling as a result of antigen retrieval was larger for epoxy sections than for LR-White sections. The immunolabeling on high-accelerator epoxy sections exposed to antigen retrieval was about 20% more intense than on untreated LR-White sections both for IgG and fibrinogen. In addition to breaking fixations bonds introduced by the chemical fixation, we believe that the antigen retrieval also breaks bonds between the epoxy resin and the embedded tissue. The combination of increased amount of accelerator during tissue processing for epoxy embedding and antigen retrieval by heating in citrate buffer is a potent method for increasing specific immunolabeling on epoxy sections.