Immunological and Biological Markers of Regression of CIN 2 in Women Under 25

Abstract

Objective: This study discusses the need for a biomarker of regression of CIN 2 in women under 25, and aims to identify such a marker.

Materials and methods: Women under 25 who were managed conservatively for CIN 2 at Dunedin Hospital Colposcopy clinic between 2005-2009 were approached for recruitment to the study (n= 59). 26 consented to use of their clinical biopsy specimens for the study.

Immunofluorescence was performed on formalin-fixed, paraffin embedded (FFPE) samples using 5 antibodies (Ki67, p53, pRb, E-cadherin and HPV E7). Results were stratified by regression status, and included samples from 12 women whose lesions ultimately regressed, and 10 from women whose CIN 2 persisted or progressed.

Results: There was no significant difference in HPV E7 positivity between the groups; 70% of regressors were E7 positive, and 77% of persisters. All four of the other markers showed a very different staining intensity and location in areas of CIN 2, when compared with areas of low grade or normal epithelium, which had weaker signal confined to the basal layer. The proliferation marker Ki67 had a non-significantly higher proliferative index (48.3% vs 37.6%, p< 0.14) in lesions destined to persist or progress. The tumour suppressors p53 and pRb both showed a weaker signal intensity in lesions that subsequently regressed, which was closer to the pattern seen in normal/adjacent epithelium. There was no difference in E-cadherin staining intensity or location between the regressors and persisters/progressors.

Despite the predicted differences in these biomarkers based upon previous research and experimental work, primarily in HPV infection, there were no significant differences in immunopositivity for any of the five markers examined between the two groups.