Ultrastructural evidence suggesting an immunomodulatory activity of oral retinoid. Its effect on dermal components in psoriasis.

The effects of the aromatic retinoid RO 10-9359 on the fine structure of psoriatic dermis were investigated by electron microscopy in five patients after 1, 2, and 3 weeks of treatment (I mg/kg/day). Our findings show that aromatic retinoid, additionally to its epidermal effects, exerts a distinct influence on dermal components in psoriasis. Ultrastructural evidence is provided suggesting that this drug stimulates lymphocytes and monocytes, promoting their differentiation into Sézary-like lymphocytic cells, activated macrophages and dermal Langerhans cells. The appearance of these immunocompetent cell lines may modulate the cell-mediated immune response in psoriasis, obviously reflecting a pharmacological action of the drug additional to its definite influence on epidermal keratinization.