PODOFILOX-INDUCED REGRESSION OF SHOPE PAPILLOMAS MAY BE INDEPENDENT OF HOST IMMUNITY

We tested the hypothesis that infiltrating leukocytes might contribute to papilloma destruction following podofilox treatment. New Zealand W hite (NZW) rabbits were inoculated with cottontail rabbit papillomavir us (CRPV) onto abraded areas of the dorsal skin. At 21 d after viral i noculation, 5.0% podofilox solution was applied to some papillomas, wh ereas others were used as controls. Three rabbits were sacrificed at e ach of three different periods after treatment initiation (1, 4, and 7 d). Four monoclonal antibodies (MoAbs), RG-16 (for B cells), L11/135 (specific for T cells), 2C4 (specific for class II antigen), and Ki67 (specific for proliferating cells), were used in an immunohistochemica l study. All positive cells and total cells in the field were counted with an ocular grid. After 1 d of treatment, proliferation of papillom a cells was strongly suppressed in treated papillomas, but leukocytic infiltration was not altered. At 4 d and 7 d of treatment, there were substantial increases (about two to three times) in the numbers of B a nd T cells and class II-expressing leukocytes. The upper layers of the papillomas were highly necrotic and cell proliferation was absent in al layers. These data support the view that podofilox has a direct tox ic effect on papilloma tissue. Leukocyte infiltration is not strongly associated with papilloma tissue and may not contribute to papilloma d estruction.