CYTOKERATIN DEMONSTRATION IN THICK BREAST-TISSUE SLICES

Tissue slices (500 to 1000 mu m thick) of archival formalin-fixed, par affin-embedded breast tissue were immunostained by a cytokeratin antib ody (MNF116) using a streptavidin-biotin complex procedure. The techni que requires prolonged exposure of tissue slices to the reagents. Use of the detergent Triton X-100 facilitated penetration of high molecula r weight reagents through the tissue slices. Fifty of 58 slices 500 mu m thick (86%) showed good to excellent immunostaining, and 13 of 20 s lices 1000 mu thick (65%) showed similar staining. Omission of the pri mary antibody eliminated any immunostaining. Comparison with correspon ding Haematoxylin staining of the thick slices (the conventional proce dure for such breast tissue slices) showed that thick-slice cytokerati n immunostaining markedly improved visualization of the epithelial str ucture in normal lobules and invasive carcinomas. Although the immunoh istochemical technique takes 33 days for completion, the quality of th e epithelial images outweighs this disadvantage.