Histopathological and immunohistochemical study of human papilloma virus infected skin

ABSTRACT

Skin specimens from twenty cases of different types of non-venereal warts [common, planter, and filiform warts] and 5 cases of venereal warts were included in this study. In addition eleven specimens of normal individuals were included as control [6 specimens from exposed sites and 5 from unexposed sites. All the patients and controls were clinically examined. The specimens. were prepared for conventional histopathological and immunohistochemical procedures for detection of HLA-DR expression by using Histostain Kit [Zymed Laboratories Inc.]. Our results revealed a highly significant decrease of HLA-DR positive Langerhans' cells [LCs] in cases of non venereal warts when compared to the control specimens obtained from exposed sites [P < 0.001]. Biopsies of venereal warts showed significant increase of HLA-DR positive LCs in comparison to non venereal warts [P < 0.001] but, showed significant decrease in comparison to the control biopsies from non-exposed sites [P < 0.001]. Keratinocytes showed negative reaction to HLA-DR in the control groups, while in non-venereal warts they showed positivity in 10 out of 20 cases [50%] and in the venereal warts they showed positivity in 4 out of 5 cases [80%]. Dermal dendrocytes showed increased reactivity to HLA-DR in both wart groups in comparison to the controls. The endothelial cells of the blood vessels were negative for HLA-DR. Study of the inflammatory components in the lesions revealed infrequent HLA-DR positive lymphocytes intermixed with strongly positive macrophages in both wart groups. In conclusion, human papilioma virus infection of the skin is associated with decrease in the number of HLA-DR positive LCs while keratinocytes and macrophages abnormally showed positive expression. Decline in HLA-DR positive LCs probably reflects LCs migration out of the epidermis and entry into regional lymph nodes leading to antigen presentation and activation of T cells. Interestingly cytoplasmic pigmentation [melanosomes] was undetectable or absent in the basal cell layer at the sites of endophytic wart growth. Human papilloma virus probably blocks the transfer of melanosomes from melanocytes to infected keratinocytes