A rapid, accurate, immunohistochemical method to label proliferating cells in the digestive tract. A comparison with tritiated thymidine.

A rapid immunohistochemical method using 5'-bromo-2'-deoxyuridine (BrdU), a thymidine analog, for labeling proliferating epithelial cells was modified and tested for accuracy against standard tritiated thymidine autoradiography (3H-TdR) in rat esophagus, stomach, duodenum, and colon. Either BrdU or 3H-thymidine or both compounds (simultaneously) were injected IP. Histological sections of these tissues were immunostained with monoclonal anti-BrdU antibody, linked to horseradish peroxidase by standard avidin-biotin techniques and stained with diaminobenzidine, or sections were dipped for autoradiography, or both techniques were applied to the same tissue section. Results showed that (a) BrdU labeled the same number of proliferating cells in all organs as 3H-TdR; (b) BrdU colabeled with 3H-thymidine; (c) immunostaining was complete in 3-4 days but standard 3H-TdR took 2 weeks; and (d) qualitative analysis took 50% less time with BrdU than with standard 3H-TdR.