IMPROVED IMMUNOGOLD LABELING OF EPOXY SECTIONS BY THE USE OF PROPYLENE-OXIDE AS ADDITIONAL AGENT IN DEHYDRATION, INFILTRATION AND EMBEDDING

The purpose of this study was to examine how the intensity of the immu nogold labeling on epoxy sections was affected by the use of propylene oxide as an agent in addition to ethanol in the dehydration and infil tration, and also to examine the effect on the immunogold labeling by adding small amounts of propylene oxide to the embedding mixture. Incr eased knowledge of the mechanism for antigen detection on resin sectio ns was another aim. Thyroid tissue, kidney tissue, and fibrin were emb edded in epoxy resin; some with ethanol as the only dehydration agent and others with propylene oxide as an additional agent in dehydration, infiltration or embedding steps in different ways. Immunogold labelin g was performed with anti-thyroglobulin, anti-IgG; and anti-fibrinogen , respectively. A higher degree of immunogold labeling was achieved by increasing the concentration of accelerator during infiltration and e mbedding (Brorson and Skjorten, 1996a, Micron, 27, 211-217). The immun ogold labeling of the sections that were based on additional dehydrati on and infiltration with propylene oxide showed significantly more int ense labeling than the sections of tissues that had only been exposed to ethanol in the dehydration and infiltration steps. The embedding of tissues in a mixture of epoxy resin and 5-10% propylene oxide gave hi gher yields of immunogold labeling than if pure epoxy resin was used f or the embedding. The improved labeling is explained by higher amplitu des of protruding antigens on the surface of the sections because anti gens are less tightly incorporated in the polymer network when using p ropylene oxide as additional agent in dehydration, infiltration or emb edding. These results illustrate the advantage of using propylene oxid e as an additional agent when preparing specimens for immunoelectron m icroscopy with epoxy resin embedding. Copyright (C) 1996 Elsevier Scie nce Ltd