Altered expression of immunoreactive involucrin in lamellar ichthyosis

In some cases of lamellar ichthyosis, mutations in the epidermal transgluta minase gene and a reduction in the thickness of the cornified envelope have been documented. Involucrin is a major component of the cornified envelope and a substrate for epidermal transglutaminase, The aim of the present wor k was to analyse the expression of involucrin in lamellar ichthyosis, An ul trastructural study and/or immunohistochemical and biochemical techniques w ith anti-involucrin antibody were carried out on the epidermis of fifteen p atients (12 families) suffering from lamellar ichthyosis. The effect of in vivo retinoid treatment on the involucrin epidermal expression was also inv estigated. Four cases with normal skin, seventeen cases of other ichthyoses and ten cases of psoriasis were used as controls. In all these cases of la mellar ichthyosis, a thin or absent cornified envelope, electron-dense gran ules inside corneocytes and a decrease of the epidermal involucrin expressi on were observed. In the patients receiving treatment with retinoids, weste rn blot and ELISA revealed an increase in the involucrin expression. The decreased expression of involucrin in lamellar ichthyosis could contrib ute to the altered desquamation process accompanying the disease, since the clinical improvement associated with retinoid treatment is accompanied by an increase in the expression of involucrin.