A QUANTITATIVE IMMUNOHISTOCHEMICAL STUDY OF THE EXPRESSION OF INTEGRINS BY NERVES IN PSORIATIC AND NORMAL SKIN

Qualitative and quantitative assessment of integrin expression by dermal nerves was made by an avidin-biotin immunoperoxidase method on snap-frozen biopsies from affected psoriatic skin, and skin from normal control subjects with no history of skin disease. Nerves expressed alpha1, alpha2, alpha3, alpha6, beta1 and beta4 integrin subunits, and perineural sheaths in the mid-dermis also expressed these subunits, with the exception of alpha2. There were more upper dermal nerve segments expressing alpha1 integrin compared with other integrins both in controls and in psoriatic skin. The greater number of nerves expressing alpha1 integrin compared with other integrins may be due to anatomical or functional differences between groups of nerves. There were significantly more nerves expressing alpha1, alpha2, alpha3, alpha6 and beta4 integrins in psoriatic skin compared with control skin. This generalized increase may indicate a secondary trophic effect on all nerves rather than a specific increase in one type of nerve. However, the expression of alpha2 integrin may be significant in the pathogenesis of the psoriatic plaque, in that it was barely detectable in the normal site-matched biopsies, but much greater in psoriatic plaques. The study of the expression of adhesion molecules by neurones in psoriasis offers a new avenue for investigation of the role of neuronal hypertrophy in the initiation and maintenance of psoriatic plaques.