In situ hybridization for the detection of human papillomavirus (HPV) in gynaecological biopsies. A study of two commercial kits.

Human papillomavirus (HPV) detection in biopsies from the lower genital tract may be requested by clinicians as a complement to ordinary histopathological diagnosis. In the present study, two commercial kits, (Enzo Diagnostics Inc., New York, USA and Biohit, Helsinki, Finland) used for in situ hybridization with biotinylated c-DNA probes were compared and the HPV-expression was evaluated in relation to histopathological findings. The Enzo kit identifies HPV-types 6/11, 16/18, 18 and 31/33/51, whereas the Biohit kit has separate probes for HPV 6, 11, 16, 18, 31 and 33, but none for HPV 51. The usefulness of a general probe (probemix) for the visualization of HPV irrespective of type (Enzo Diagnostics Inc.) was also studied Altogether 226 biopsies from the lower female genital tract were formalin-fixed, paraffin-embedded and processed for routine histopathological grading. Consecutive sections were employed for in situ hybridization. 50 biopsies were subject to double-testing with Enzo and Biohit, whereas 176 were tested with Enzo only. Of the double-tested biopsies, 30% displayed a nuclear staining with the Enzo kit and 28% with the Biohit kit. It is concluded that the probes of these two kits have the same sensitivity in detecting HPV in tissue sections. Condylomata acuminata were HPV-positive in 81%, mostly for types 6/11. Flat condylomas were HPV-positive in 35%. The HPV-positivity of biopsies with low grade SIL (I) was 50% and that of high grade SIL (II and III) was 37%. High grade SIL contained either HPV-types 16/18 or 31/33/51. A correlation was found between the occurrence of koilocytosis and the presence of HPV-DNA. HPV-expression was most easily visualized in condylomata acuminata. In epithelium of normal appearance or with inflammatory alterations HPV-DNA was not seen.