Expression of interleukin-6-like molecules and tumour necrosis factor after topical treatment of psoriasis with a new vitamin D analogue (MC 903).

Skin biopsies from 5 patients with chronic plaque psoriasis were examined to test the effect of topical treatment with a new synthetic vitamin D3 analogue, MC 903, on epidermal interleukin 6 (IL-6) and tumour necrosis factor alpha (TNF alpha). Skin biopsies, taken before therapy and after one and 2 weeks of therapy were examined immunohistologically. IL-6 was visualized using a partially purified polyclonal antiserum to crude supernatants of activated human blood monocytes before and after absorption with recombinant human IL-6. TNF alpha was demonstrated using a specific polyclonal antiserum to human recombinant TNF alpha. Both the intensity and extension of staining for IL-6, but not for TNF alpha, were increased in lesions compared with unaffected skin. During therapy with MC 903 a decline in the staining intensity for IL-6, but not for TNF alpha, was observed in both lesional and unaffected skin. Placebo-treated lesions, however, remained unchanged.