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Podofilox-induced regression of Shope papillomas may be independent of host immunity
M Okabayashi1, M D Pickel, L R Budgeon
1Department of Pathology, Milton S. Hershey Medical Center, Pennsylvania State University, Hershey 17033.
Abstract:
We tested the hypothesis that infiltrating leukocytes might contribute to papilloma destruction following podofilox treatment. New Zealand White (NZW) rabbits were inoculated with cottontail rabbit papillomavirus (CRPV) onto abraded areas of the dorsal skin. At 21 d after viral inoculation, 5.0% podofilox solution was applied to some papillomas, whereas others were used as controls. Three rabbits were sacrificed at each 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 immunohistochemical study. All positive cells and total cells in the field were counted with an ocular grid. After 1 d of treatment, proliferation of papilloma 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 and T cells and class II-expressing leukocytes. The upper layers of the papillomas were highly necrotic and cell proliferation was absent in all layers. These data support the view that podofilox has a direct toxic effect on papilloma tissue. Leukocyte infiltration is not strongly associated with papilloma tissue and may not contribute to papilloma destruction.
Insights
Podofilox treatment directly harms papilloma cells, suppressing their growth. While immune cells increase later, they do not appear to cause papilloma destruction.
Area of Science:
- Immunology
- Dermatology
- Virology
Background:
- Papillomas are skin growths caused by viruses.
- Podofilox is a treatment used for certain skin conditions.
- The role of the immune system in papilloma treatment response is not fully understood.
Purpose of the Study:
- To investigate the effect of podofilox on papilloma cells.
- To determine if infiltrating leukocytes contribute to papilloma destruction after podofilox treatment.
Main Methods:
- New Zealand White rabbits were inoculated with cottontail rabbit papillomavirus (CRPV).
- Podofilox treatment was applied to induced papillomas.
- Immunohistochemical analysis using monoclonal antibodies (RG-16, L11/135, 2C4, Ki67) was performed on papilloma tissue collected at 1, 4, and 7 days post-treatment.
- Cell proliferation and leukocyte infiltration were quantified.
Main Results:
- Podofilox treatment suppressed papilloma cell proliferation within 1 day.
- Leukocyte infiltration (B cells, T cells, class II-expressing cells) significantly increased at 4 and 7 days post-treatment.
- Papilloma tissue showed necrosis and absence of cell proliferation in the upper layers by 4 and 7 days.
- No strong association was found between leukocyte infiltration and papilloma tissue destruction.
Conclusions:
- Podofilox exhibits a direct cytotoxic effect on papilloma cells.
- Leukocyte infiltration does not appear to be the primary mechanism for podofilox-mediated papilloma destruction.