Cell biology of cultured anogenital warts

HPV-DNA is not detectable in outgrowing cells from explant cultures of skin lesions established at the air-liquid-interface

Keratinocyte cultures established from HPV containing skin cancers were described earlier to lose their HPV DNA after passaging in vitro. A different approach was therefore used in this study. Explant cultures were generated by depositing small pieces of various benign and (pre)malignant skin specimens of renal transplant recipients and non-immunosuppressed patients on fibroblast-populated collagen lattices or on de-epidermized dermis. Subsequently, the cultures were maintained at the air-liquid interface. At various time points, samples were collected for both HPV analysis, using a nested PCR approach, and morphology. The outgrowing keratinocytes developed into multilayered epithelial structures showing terminal differentiation. No histological differences were observed between cultures established from HPV positive and negative lesions. Eighteen biopsy specimens were tested for their HPV content before and after culture. Before culture 11 out of these skin specimens contained DNA of the Epidermodysplasia Verruciformis-related HPV types (EV-HPV). Comparison of the HPV types detected in two different parts of the same skin specimen before culture was strongly suggestive for a non-homogeneous distribution of EV-HPV in the lesions. From the explant cultures derived from the 11 HPV-positive biopsies, 31 samples from the originally explanted pieces of tissue and 38 samples from the outgrowing multilayered epithelial sections were collected. HPV DNA was detected in 10 of the 31 and in 3 of the 38 samples (Chi-square test, P = 0.01), respectively. These results indicate that EV-HPV positive keratinocytes do not efficiently proliferate or lose their HPV DNA in this culture system or EV-HPV DNA is present in only a few basal cells, making it improbable that these cells are located at the outgrowing margins.

Production of TNF-alpha by primary cultures of human keratinocytes challenged with loxosceles gaucho venom

Primary cultures of human keratinocytes were challenged with increasing doses from 10 ng/mL to 2 &mgr;g/mL of Loxosceles gaucho venom, responsible for dermonecrotic lesion in humans. TNF-alpha was investigated by bioassay and ELISA in the supernatant of the cultures challenged with 100 ng/mL, 500 ng/mL, 1 and 2 &mgr;g/mL of venom. TNF-alpha was detected by bioassay in the supernatant of cultures challenged with 100 ng/mL, after 6 h. The cytokine was detected by ELISA in the supernatant of the cells challenged with doses of l &mgr;g/mL, after 6 and 12 h. The results point out the capacity of this venom to activate the keratinocytes in primary cultures to produce TNF-alpha. The production of cytokines could contribute to the local inflammatory process in patients bitten by Loxosceles sp.

The clinical management and laboratory assessment of anal warts

The results of a clinical and virological survey of anal warts from 85 predominantly homosexual or bisexual men is presented, together with an improved technique for the surgical treatment of these lesions. Two types of anal warts, which were classified as either "acute" or "chronic" on the basis of their appearance and clinical behaviour, were recognized commonly. However, our laboratory investigations--which consisted of the routine histopathological examination of all specimens, together with immunohistochemical testing for the common wart antigen of specimens from 30 patients and papillomavirus typing by human papillomavirus DNA probing of 27 specimens--failed to reveal any significant differences between the two classes of anal warts. By means of a dot hybridization technique with mixed human papillomavirus DNA probes for types 6 and 11 and types 16 and 18, all wart biopsy specimens that were tested were shown to contain human papillomavirus types 6/11; two specimens also contained human papillomavirus types 16/18. Southern blot hybridization studies of eight specimens revealed that five warts contained human papillomavirus type 6 only and three warts contained human papillomavirus type 11 only. Although the surgical technique that is described was successful in terms of patient acceptance and the eventual eradication of anal warts, there was a high rate of recurrence of the lesions, which necessitated repeat operations in two-thirds of the patients. The need for counselling before surgery and for regular follow-up examinations after surgery is discussed.