VITILIGINOUS VS PIGMENTED SKIN-RESPONSE TO INTRADERMAL ADMINISTRATIONOF INTERFERON-GAMMA

Background and Design.-Decreased sensitization and elicitation of cont act allergens in vitiliginous skin has been described. This may be rel ated to altered epidermal Langerhans cell migration with bound hapten to dermis and draining lymph nodes. The aim of the present study was t o detect the potential ability of vitiliginous skin to respond to an i n vivo immunologic stimulus such as intradermal injections of interfer on gamma (IFN-gamma). Vitiliginous and normal pigmented skin of each p atient was injected intradermally with 10 mug of recombinant IFN-gamma diluted in 0.1 mL of sterile water for 3 consecutive days. On day 5, punch biopsy specimens were obtained from the injected sites. Histolog ic and immunohistochemical staining was performed on all sections. The cryostat sections were stained with adenosine triphosphatase as well as with the indirect immunoperoxidase technique employing murine monoc lonal antibodies to HLA-DR, ICAM-1, CD1, CD11a, and CD18. Results.-HLA -DR and ICAM-1 expression by epidermal cells, combined with perivascul ar accumulation of mononuclear cells with CD11a and CD18 expression, w as observed in all sites injected with IFN-gamma. However, absence of an effect on the epidermal Langerhans cell population was noted only o n the vitiliginous skin. Conclusion.-The reactivity of depigmented and pigmented skin was found to be different after IFN-gamma administrati on, with fewer CD1-positive cells in the depigmented skin. As adenosin e triphosphatase staining also showed fewer positive cells, it may be concluded that no effect on the migration of epidermal Langerhans cell s was noted in the involved skin. This may shed light on the immunolog ic aberration seen in vitiliginous skin.