EVIDENCE FOR A STREPTOCOCCAL SUPERANTIGEN-DRIVEN PROCESS IN ACUTE GUTTATE PSORIASIS

Recent studies have suggested that T cells play a critical role in the pathogenesis of psoriasis, Guttate psoriasis is a well-defined form o f psoriasis frequently associated with streptococcal throat infection. This study tested the hypothesis that T cells in acute guttate psoria sis skin lesions may be activated by streptococcal superantigens. Peri pheral blood as well as lesional and perilesional skin biopsies were a nalyzed for T cell receptor V beta repertoire using monoclonal antibod ies against 10 different V beta families, Skin biopsies from all patie nts with acute guttate psoriasis, but not skin biopsies from patients with acute atopic dermatitis or inflammatory skin lesions induced in n ormal subjects with sodium lauryl sulfate, demonstrated selective accu mulation of V beta 2+ T cells (P < 0.05). The expansion of V beta 2+ T cells occurred in both the CD4+ acid the CD8+ T cell subsets. Sequenc e analysis of T cell receptor beta chain genes of V beta 2-expressing T cells from skin biopsies of patients with guttate psoriasis showed e xtensive junctional region diversity that is more compatible with a su perantigen rather than a conventional (nominal) antigen-driven T cell response. All streptococcal isolates from patients with guttate psoria sis secreted streptococcal pyrogenic exotoxin C, a superantigen known to stimulate marked V beta 2+ T cell expansion, These data support the concept that acute guttate psoriasis is associated with superantigeni c stimulation of T cells triggered by streptococcal superantigen(s).