Increased PCNA/cyclin index correlates with severity of duodenitis defined by histological criteria.

The proliferative activity of crypt epithelial cells was studied in 64 duodenal biopsies using immunohistochemistry and proliferating cell nuclear antigen (PCNA)/cyclin monoclonal antibodies in alcohol-fixed paraffin-embedded sections. A positive correlation between duodenitis as defined by histological criteria and increased mean percentage of PCNA positive crypt cell nuclei (PCNA index) was found. The mean PCNA index in normal mucosa was 11.8 +/- 2.7% (mean +/- SD), in mild (grade 1) duodenitis 17.3 +/- 3.9%, in moderate (grade 2) 30.6 +/- 6.9%, and in severe (grade 3) duodenitis 41.1 +/- 8.5%. The inclusion of PCNA index, which is easily measured in paraffin-embedded sections, in the existing histopathological grading systems of duodenitis may improve their clinical relevance.