DNA FLOW-CYTOMETRY OF FRESH AND PARAFFIN-EMBEDDED TISSUE USING CYTOKERATIN STAINING

DNA flow cytometry measurements were performed using cytokeratin as a second parameter to identify epithelial cells selectively in fresh and in archival paraffin samples of normal and adenocarcinoma tissues fro m breast and colon. Fresh specimens consisted of 22 adenocarcinomas of breast, 20 adenocarcinomas of colon, 16 control breast samples, and 1 3 control colon samples. Paraffin block specimens consisted of 22 aden ocarcinomas of breast (the same as fresh samples), 20 adenocarcinomas of colon (the same as fresh samples), 37 control breast samples and 34 control colon samples. The average proportion of cytokeratin-positive cells per group ranged from 31 to 55% for fresh samples and from 14 t o 34% for paraffin samples. For aneuploid cells populations of adenoca rcinomas, which consist only of epithelial cells, the average percenta ge of cytokeratin-positive cells ranged from 60 to 72%. The technique gave satisfactory measurements of ploidy and of cell cycle data in bot h types of samples. Cell cycle measurements were less accurate than pl oidy measurements in both types of samples, and multiple sampling will be required for adequate accuracy. The average S-phase fraction of cy tokeratin-positive cells ranged from 6 to 15% for fresh specimens and from 11 to 20% for paraffin samples. Similar data were obtained for th e proliferative index (G1 + S + G2 + M phases). The coefficients of va riation were smaller for proliferative index than for S-phase fraction data, indicating greater accuracy. Paraffin data give higher cycling cell measurements than corresponding fresh data, so separate standardi zation of measurements may be required for fresh and for paraffin data .