Altered binding of Ulex europaeus I lectin to psoriatic epidermis

We have used Ulex europaeus I (UEA I) lectin, specific for alpha-L-fucose-containing glycoconjugates, in fluorescence microscopy to stain cryostat sections of human skin from normal persons and patients with psoriasis and lichen simplex. In normal skin the upper layers of the stratum spinosum and the stratum granulosum were strongly reactive with UEA I, whereas the lower layers of the epidermis did not react. The staining intensity of the upper epidermis was similar to that of the endothelium of dermal blood vessels. Biopsies of the lesional skin of lichen simplex showed an intense UEA I-specific staining throughout the whole epidermis, similar in intensity to that seen in the upper epidermis of normal skin. In psoriatic lesions positive UEA I-specific fluorescence was seen throughout the whole epidermis, but the fluorescence was more faint and often granular. In uninvolved skin of psoriatic patients the whole epidermis showed a diffuse UEA I-specific fluorescence, differing in this respect from normal skin. In normal skin UEA I binds to epidermal cells which are at a certain state of differentiation. The results with psoriatic epidermis confirm that both uninvolved and lesional epidermis have a defect in epidermal maturation, as shown by the altered binding of UEA I lectin.