Interferon in suction blister fluid from psoriatic lesions.

Interferon (IFN) (at least 16 units/ml) was demonstrated in suction blister fluid obtained from lesional skin in nine of thirteen patients with psoriasis vulgaris and in two patients with allergic contact dermatitis, but not in blister fluid from unaffected skin. IFN was detected in only three of the sera from the patients with psoriasis. The difference in results between the blister fluid and the sera from these patients was statistically significant (P less than 0.025). Evidence was obtained which indicated that the activity was probably IFN-gamma (immune IFN), but the additional presence of IFN-alpha in some of the fluids could not be excluded. The data indicate that IFN is produced locally in the psoriatic lesions, most likely by activated T lymphocytes.