DECREASED T-CELL REACTIVITY TO TRYPSINIZED GROUP-A, TYPE M22 STREPTOCOCCI IN PSORIASIS

The proliferative responses of peripheral blood mononuclear cells from patients with guttate and chronic plaque psoriasis to streptococcal M protein were investigated using whole and trypsinized group A M22-pos itive streptococci. Peripheral blood mononuclear cell responses to who le type M22 group A streptococci were significantly increased in gutta te, but not chronic plaque, psoriasis patients compared to 17 non-psor iatic controls (p < 0.05; n = 17). A significant reduction of this res ponse was observed in both guttate (p < 0.001; n = 17) and chronic pla que (p < 0.01; n = 27) psoriatic patients, but not in the control grou p, after repeated trypsinization to remove M protein from the streptoc occi. Furthermore, the difference between the peripheral blood mononuc lear cell response to untrypsinized and trypsinized streptococci was s ignificantly greater in the guttate patients than in the controls p < 0.02). This preliminary study has shown an increased reactivity of T l ymphocytes with specificity for trypsin-sensitive protein expressed by type M22 streptococci in the peripheral blood of patients with psoria sis.