RECOGNITION OF STREPTOCOCCUS-PYOGENES AND SKIN AUTOANTIGENS IN GUTTATE PSORIASIS

Background: Guttate psoriasis is associated with infections by Strepto coccus pyogenes and cross-reactions between skin and streptococcal ant igens have been reported, suggesting an autoimmune component in the di sease, Methods: In this work, the authors looked for antibodies agains t S. pyogenes M-5 antigens by immunoblot in 52 sera of psoriasis patie nts and in 52 sera of normal individuals. Histological and immunohisto chemical analysis in skin biopsies from lesions of another group of 16 clinically diagnosed guttate psoriasis patients and four healthy cont rols were also carried out. Results: All guttate psoriasis patients st udied (11) had IgG antibodies that intensively recognized three differ ent proteins of 70, 60 and 14 kDa, as compared to sera from patients w ith other forms of psoriasis or from healthy controls. The diagnosis o f psoriasis was confirmed in 14 of the patients by hematoxylin-eosin s taining, Of the other two patients, one was diagnosed as parapsoriasis and the other as liquen, By indirect immunofluorescence (IFI), all 14 psoriatic patients had autoantibodies against their own lesional skin that did not recognize normal skin from control subjects or from the two non-psoriatic patients. The parapsoriatic and the liquen patients did not have autoantibodies. A rabbit immune serum against S, pyogenes antigens reacted with lesional skin from the 14 guttate psoriatic pat ients, but not with normal skin from controls or with lesional skin fr om the 2 non-psoriatic patients, Conclusions: The recognition by immun oblot of streptococcal antigens by serum of guttate psoriasis patients , the presence of autoantibodies against their own skin, and recogniti on of the same skin antigens by anti-streptococcal rabbit antibodies c onfirm the participation of the immune system and of streptococcal inf ections in guttate psoriasis.