MICROWAVE ANTIGEN RETRIEVAL IN IMMUNOCYTOCHEMISTRY - A STUDY OF 80 ANTIBODIES

Aims-To evaluate the effect of microwave irradiation on the staining q uality of a range of commonly used primary antibodies in archival, for malin fixed, paraffin wax embedded material, with emphasis on antibodi es that have previously worked successfully only on frozen tissue. Met hods-Immunocytochemistry (streptavidin-biotin complex technique) was p erformed on histological sections of a range of normal and pathologica l tissues, after varying treatment with microwave irradiation. The sta ining quality of each antibody was compared with that achieved without prior treatment of the sections or after enzyme predigestion. Results -Microwave irradiation permitted successful immunostaining with 20 ant ibodies that stained only frozen tissues before. The staining characte ristics of 21 antibodies that were already known to stain formalin fix ed, paraffin wax embedded material were improved. Another 39 antibodie s did not show enhanced staining with microwave irradiation. The metho d preserves tissue morphology and produces more consis- tent staining than that achieved by enzyme predigestion with many antibodies. Microw ave irradiation may also allow some primary antibodies to be used at h igher working dilutions. The citrate buffer used in this study avoids the necessity of exposure to heavy metal salts. Conclusions-Microwave antigen retrieval represents an important technical advance within imm unocytochemistry that will greatly increase the range of antibodies wh ich can be used to study formalin fixed, paraffin wax embedded tissues .