The role of factor XIIIa-positive dermal dendrocytes in HIV-1-positive psoriatics.

Factor XIIIa-positive dermal dendrocytes (FXIIIa+ dd) may have an important role in the pathogenesis of psoriasis, in that their numbers are increased in lesional skin compared with non-lesional skin. Moreover, in AIDS-associated Kaposi's sarcoma the number of these cells is also increased, in comparison with the classical type of Kaposi's sarcoma. In addition, patients suffering from HIV-1 infection may develop severe psoriasis. The aim of this study was to examine the distribution of FXIIIa+ dd in lesional and non-lesional skin from seven psoriatic patients with positive HIV-1 serology, and compare the results with age-, sex-, and site-matched HIV-1-negative psoriatic patients. In both patient groups there was an increase of FXIIIa+ dd in the papillary dermis in lesional skin, compared with non-lesional skin (HIV+ [P = 0.007]; HIV- [P = 0.0006]). Positive cells were also observed within the epidermis in lesional skin in both groups. However, there was no significant difference between HIV-1+ and HIV-1- groups in the number of FXIIIa+ dd in the epidermis and dermis (P > 0.05). These findings suggest that, if FXIIIa+ dd do have a role in psoriasis, deterioration of this condition in HIV-1+ patients is not due to proliferation of dermal dendrocytes.