Reduced density of T6-positive epidermal Langerhans' cells in uninvolved skin of patients with psoriasis.

The Langerhans' cell (LC) density is known to be reduced in skin lesions as compared to uninvolved skin in patients with psoriasis. It is, however, still unsettled whether the LC density in uninvolved psoriatic skin differs from the density in normal skin. We have enumerated epidermal LC in uninvolved skin from 15 patients with stable psoriasis and in 15 healthy subjects. Punch biopsies from non-sunexposed skin from the buttock were taken. Epidermal sheets were separated by EDTA and LC then stained with an indirect immunoperoxidase technique using the mouse monoclonal antibody OKT6. The LC density was significantly reduced in uninvolved skin of patients with psoriasis (mean +/- SD: 375 +/- 37/mm2) as compared to healthy controls (544 +/- 168/mm2) (p less than 0.01). A reduced number of LC in uninvolved psoriatic skin is in accordance with previous reports demonstrating an impaired DNCB reactivity in patients with psoriasis. Whether the reduction in LC density is of pathogenic importance for psoriasis is unknown.