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 of psoriasis frequently associated with streptococcal throat infection. This study tested the hypothesis that T cells in acute guttate psoriasis skin lesions may he activated by streptococcal superantigens. Peripheral blood as well as lesional and perilesional skin biopsies were analyzed for T cell receptor Vβ repertoire using monoclonal antibodies against 10 different Vβ families. Skin biopsies from all patients with acute guttate psoriasis, hut not skin biopsies from patients with acute atopic dermatitis or inflammatory skin lesions induced in normal subjects with sodium lauryl sulfate, demonstrated selective accumulation of Vβ2 + T cells (P < 0.05). The expansion of Vβ2 + T cells occurred in both the CD4+ and the CD8+ T cell subsets. Sequence analysis of T cell receptor β chain genes of Vβ2- expressing T cells from skin biopsies of patients with guttate psoriasis showed extensive junctional region diversity that is mare compatible with a superantigen rather than a conventional (nominal) antigen-driven T cell response. All streptococcal isolates from patients with guttate psoriasis secreted streptococcal pyrogenic exotoxin C, a superantigen known to stimulate marked Vβ2 + T cell expansion. These data support the concept that acute guttate psoriasis is associated with superantigenic stimulation of T cells triggered by streptococcal superantigen(s).