Enzymatic quantification of polymorphonuclear leucocytes in normal and psoriatic skin following standardized injury

The intra‐epidermal accumulation of polymorphonuclear leucocytes (PMN) following sellotape stripping of psoriatic non‐lesional skin and normal skin of healthy individuals has been quantified with the elastase assay. Far more PMN accumulated in the skin in unstable psoriasis than in stable psoriasis. No significant difference was found, however, in PMN accumulation between the psoriatics as a whole and the controls. PMN accumulation was followed by the induction of an elastase inhibitor in psoriatic patients and controls. No significant differences could be found in inhibitory activity between controls and psoriatics. Our results suggest that the degree of PMN accumulation following surface trauma is essentially normal in stable chronic plaque psoriasis, but increases in unstable phases of the disease.