The effect of interferon on human papillomaviruses associated with cervical intraepithelial neoplasia

Summary. A double-blind, placebo-controlled, trial of leucocyte interferon showed that, contrary to previous reports, interferon had no significant effect on cervical intraepithelial neoplasia (CIN) when applied topically in a geld. DNA hybridization of cervical scrapes was used to monitor the effect of interferon on the human papillomaviruses (HPV) associated with CIN. There was, however, no significant difference in the expression of HPV 6 or 16 in the cervical epithelium of patients treated with interferon compared with those given a placebo. By using superficial cells scraped from the surface of the cervical epithelium as a source of DNA for viral studies, we were able to investigate the relation between HPV and CIN without interfering withthe natural history of the disease. HPV 16 was detected in lesions which persisted while HPV 6 only was detected in one lesion that regressed. Regression was clearly associated with reduction in the number of copies of viral DNA per cell in this case. Dual infection with HPV types 6 and 16 were recorded in two patients with persistent lesions. In one patient, hybridization studies indicated that infectionwith HPV 16 could have occurred after infection with type 6 was established, and it is postulated that this may have changed the nature of the cervical lesion.