DETECTION OF APOPTOSIS IN COLORECTAL-CARCINOMA BY LIGHT-MICROSCOPY AND IN-SITU END LABELING

OBJECTIVE: An in situ end labelling reaction (ISEL) was recently descr ibed for the detection of apoptotic cells in histologic sections. We c ompared the efficiency and reproducibility of this assay with those of routine light microscopy using hematoxylin and eosin (H&E) in the qua ntitation of apoptotic cells in colorectal enticer. STUDY DESIGN: Para ffin-embedded archival tissues from 15 colorectal carcinomas were used in the study. ISEL was performed using terminal deoxynucleotidyl tran sferase, biotinylated deoxyuridine triphosphate and streptavidin-alkal ine phosphatase. RESULTS: Apoptotic indices determined by the two assa ys showed a strong positive correlation (Pearson coefficient 0.82), wi th the ISEL assay detecting twice the number of apoptotic cells as tha t seen with H&E staining. Both assays showed significant interobserver and intraobserver variation, while the ISEL assay also showed conside rable interassay variability and was less cost-effective than H&E in t he detection of apoptotic cells. CONCLUSION: In the light microscopic quantitation of apoptosis in colorectal tumors, the ISEL assay offered no greater reproducibility, and was less cost-effective, than routine H&E staining.