LOCAL IMMUNE-RESPONSES IN CUTANEOUS WARTS - AN IMMUNOCYTOCHEMICAL STUDY OF LANGERHANS CELLS, T-CELLS AND ADHESION MOLECULES

Cutaneous warts, caused by infection with human papillomavirus (HPV) f requently persist for months or years; it is not clear what aspects of the immune system are most important in their control and resolution. The present study concentrated on an immunocytochemical analysis of L angerhans' cells and T cells in cutaneous warts together with an asses sment of adhesion molecule expression (ICAM-1 and ELAM-1). Comparisons were made throughout with skin from normal subjects and from patients with psoriasis. There was an increase in numbers of CD3(+) (pan T), C D45RO(+) (memory T) cells in the dermis of warts compared with normal skin. In addition ICAM-1 and ELAM-1 expression were increased in the d ermis of warts compared with normal skin which may be responsible for the influx of T cells into this site. However, a large reduction of CD 3(+) CD45RO(+) T cells was seen in the epidermis of warts compared wit h normal skin, and epidermal ICAM-1 was not observed in warts. In 75% of the warts studied epidermal Langerhans' cell numbers were reduced i n comparison with normal or psoriatic skin. Thus, a decrease in Langer hans' cells and a lack of adhesion molecule expression in the epidermi s of warts may lead to a reduced influx of T cells into the lesion its elf, although T cells are evidently present in the dermis underlying t he infected site. It is possible that these local effects are induced by factors produced from keratinocytes as a result of HPV infection.