PSORIASIS - A T-CELL-MEDIATED AUTOIMMUNE-DISEASE INDUCED BY STREPTOCOCCAL SUPERANTIGENS

Psorinsis is a T-cell-mediated disease that can be triggered by infection with group A beta-haemolytic streptococci. It is proposed that psoriatic skin lesions are initiated by exotoxin-activated T cells, and persist because of specific T cells that react both with streptococcal M protein and a skin determinant, possibly a variant of Keratin. As discussed here by Helgi Valdimarsson and colleagues, cytokines released by the superantigen (SAg)-stimulated T cells could induce or enhance the expression of the crossreactive autoantigen, lending to the rescue and activation of autoreactive T cells. In this way, the SAg-determined T-cell receptor V beta phenotype would be maintained by T cells in psoriatic lesions.