In situ localization of interferons in psoriatic lesions.

An indirect immunofluorescence technique, using murine monoclonal antibodies (MoAbs) against human IFN-alpha and human IFN-gamma was used to study IFNs in cryostat sections from psoriatic skin lesions. The IFNs were more pronounced in sections from highly active psoriasis than in sections from stationary psoriasis. In highly active psoriatic lesions IFN-alpha was localized to keratinocytes is stratum basale, to some epidermal dendritic cells, probably Langerhans cells, and to some mononuclear cells in dermis. IFN-alpha was usually not detected in sections from stationary psoriasis. IFN-gamma was localized to stratum corneum, to keratinocytes around microabcesses and to mononuclear cells in the dermal cell infiltrates, predominantly in highly active psoriatic lesions. Both IFN-alpha and IFN-gamma were localized to some endothelial cells in the papillary dermis. The MoAbs did not stain sections from unaffected skin from patients with psoriasis or sections from healthy individuals. The findings indicate that the IFN system in the skin may be of significance in the pathophysiology of psoriasis.