Previous studies from our laboratory suggested that architectural alterations of the cell membranes may have a major significance in the pathogenesis of psoriasis. Consequently, the membrane-bound Mg++ activated ATP-hydrolytic activity was investigated in normal and psoriatic epidermis under the electron microscope.
The present study revealed that, in contrast to normal epidermis, only minimal ATP-hydrolytic activity is present on the cell membranes of psoriatic keratinocytes. This finding may reflect either a diminished attachment of substrate on the altered cell surface or an enzyme defect of the cell membrane. In both cases the reduced interaction between ATP and membrane-bound ATP-hydrolysing enzymes represents a functional membrane disorder of the psoriatic keratinocyte, presumably resulting in an insufficient utilization of ATP for active transport mechanisms on the cell surface.