ASSESSMENT OF KI-67 ANTIGEN IMMUNOSTAINING IN SQUAMOUS INTRAEPITHELIAL LESIONS OF THE UTERINE CERVIX - CORRELATION WITH THE HISTOLOGIC GRADE AND HUMAN PAPILLOMAVIRUS TYPE

A formalin-fixation and paraffin-processing resistant epitope of Ki-67 cell proliferation-associated antigen was immunohistochemically detec ted by the MIB-1 monoclonal antibody (Immunotech, Marseille, France) i n 25 routinely processed cervical biopsies showing normal squamous epi thelium or squamous metaplasia and in 65 cervical intraepithelial lesi ons (SILs) (44 low grade and 21 high grade SILs) with human papillomav irus (HPV) infection. Expression of Ki-67 antigen was exclusively conf ined to the parabasal and basal layers of normal and metaplastic epith elium, There was no significant difference of Ki-67 antigen immunostai ning between normal cervical biopsies and cases of squamous metaplasia , In SIL specimens, the staining was markedly increased in the parabas al and basal layers and Ki-67-positive cells were also distributed in the intermediate (low grade SIL) or all layers of epithelium (high gra de SIL), Statistically significant differences for the density of Ki-6 7 antigen-labeled cells, which were assessed with an image analysis sy stem, were found in comparisons between normal or metaplastic epitheli um and SILs (P < .001) and between low grade SILs and high grade SILs (P < .001). In our series of SILs, HPV 16/18 and 31/33/35/novel types, which were found in both low grade and high grade SILs, were signific antly associated with higher densities of Ki-67 antigen-positive cells than HPV 6/11 types that were found exclusively in low grade SILs. Th ere was no significant difference found between the densities of Ki-67 antigen-labeled cells in NPV 16/18-positive and HPV 31/33/35/novel ty pes-positive tissues in our series of SILs taken as a whole or when se gregating SILs into low grade and high grade.