A useful low temperature method for post-embedding electron immunocytochemistry in routine histopathology.

Using a low temperature resin, we have developed a reliable technique for post-embedding electron immunocytochemistry which is rapid enough to be used in a routine histopathology laboratory. Glutaraldehyde fixed human tissues were dehydrated and embedded at -25 degrees C in a new acrylic resin called LR-Gold. Using the immunogold technique, ultra-thin sections of the tissues were labelled with monoclonal antibodies to cytokeratin, human milk fat globule and HLA-D region antigen; and with polyclonal antisera to lysozyme, kappa and lambda light chains and immunoglobulin M. The resin was easy to section and the preservation of fine structure was excellent. Immunolabelling procedures gave clean and consistent results, and electron micrographs of examples of this are included. It was felt that the preservation of ultrastructure and antigenicity compared well with the results of other workers using low temperature resins such as Lowicryl K4M, but LR-Gold was superior to Lowicryl K4M because sectioning was considerably easier and the sections were more stable in the electron beam.