Cyclic adenosine monophosphate-phosphodiesterase activity in cultured keratinocytes from patients with atopic eczema.

A number of previous studies have documented an increase in cyclic adenosine monophosphate-phosphodiesterase activity in patients with atopic dermatitis. We have studied the activity of this enzyme in keratinocytes cultured from patients with atopic dermatitis compared to keratinocytes from non-atopic controls. Results show that these pure preparations of keratinocytes express only one form of cyclic adenosine monophosphate phosphodiesterase with a Km of 1.9 microM, and a Vmax of 17 pmol/min/mg of substrate converted. We conclude that cyclic adenosine monophosphate-phosphodiesterase activity in cultured keratinocytes from patients with atopic eczema does not differ from controls.