Intradermal antigen tests in psoriasis
McFadden, J.P.; Powles, A.V.; Baker, B.S.; Valdimarsson, H.; Fry, L.
Acta Dermato-Venereologica 70(3): 262-264
1990
ISSN/ISBN: 0001-5555 PMID: 1972847 Document Number: 359696
To assess whether elicitation of delayed hypersensitivity may be superior to trauma in inducing the Koebner reaction in psoriasis, 12 affected patients and 9 control subjects were tested with 0.1 ml intradermal injection of streptokinase/streptodornase (20 .mu./5 .mu. per 0.1 ml), PPD (1 in 1000) and saline control solutions in a double-blind study; Koebner status was also established in the psoriatic patients. Injected sites were examined at 48 ha and 7, 14, 21 and 28 days for local development of psoriasis, erythema and induratoin (diameter). One patient was Koebner-positive and developed psoriasis at all three injection sites. The other, Koebner-negative psoriatic subjects did not develop psoriasis locally. However, compared with non-psoriatic controls they showed a marked delay in resolution of the delayed hypersensitivity reaction to the PPD antigen and a similar but less marked phenomenon was observed for streptokinase/streptodornase. These findings indicate that intradermal antigen, of the nature and amount used in this study, is no more effective in inducing the Koebner phenomenon than injury alone. However, the ability of psoriasis patients to switch off cell-mediated immune reaction appears to be impaired.