RESUMO
Objectives: Fixed drug eruption is a common distinct variant of druginduced dermatoses. Although effector and regulatory T cells play roles in the progression and resolution of FDE, respectively, little in- vivo data exist regarding the T cell dynamics in the pathogenesis of FDE. The aim of this study was to through some light on the pathogenesis of FDE through in-situ study of the immunostaining with CD4, CD8 and HLA-DR. Design: Thirty patients with FDE, [16 females and 14 males], their ages ranged between 6 and 54 years with mean 19.6 years old, were included in this study, in addition to 10 normal, age and sex matched, control subjects Settings: Dermatology and Pathology Departments, Menoufiya Faculty of Medicine
Intervention: skin biopsies were taken from 16 active and 14 healed lesions of FDE besides 20 control biopsies [10 biopsies from lesionalnearby, skill and 10 normal skin]. H and E stained sections were subjected to ordinary pathological examination. Three unstained sections from each biopsy were prepared on poly-L lysine coated slides and subjected to immunostaining withCD4, CD8 and HLA-DR. Serum Ca, total and ionized, was measured
Results: In acute FDE lesions, H and E sections revealed prominent dermal inflammatory cells infiltrating the epidermis in 100% of cases, hydropic degeneration, spongiosis and dyskeratosis besides melanin in- continence; In healed lesions, H and E stained sections revealed epidermal atrophy and there was perivascular inflammatory infiltrate. The immunostaining of HL4-DR was evident with strong expression in the inflammatory cells in dermis [mmmcl epidermis. The immunostaining of active lesions showed CD8+ T cells and CD4 + T cells in both the epidermis and dermis. In healed lesions, CD8+ T cells were detected in 93% in the epidermis and CD4 + T cells were detected in 21.4% of lesions. Serum Ca was statistically decreased in patient than in control group
Conclusions: Activation of T cells residing in the resting FDE lesions, by ingestion of a causative drug can rapidly produce large amounts of IFN gamma followed by localized epidermal injury. Such early IFN gamma production in-situ was only observed in the intraepidermal resident T cells in the lesions but not those in the peri-lesional skin and consequently progressed to localized epidermal injury. The in-situ studies indicated that CD8 + ve T cells persist in a state of activation in the resting FDE lesions and are capable of acquiring potent cytotoxic activity with rapid kinetics on clinical challenge