The aim of this study was to determine whether levels of biologically active
calmodulin are elevated in both lesional and uninvolved epidermis in
psoriasis. Epidermal shave biopsies were obtained from normal controls and from both psoriatic plaques and nonlesional psoriatic skin. Following determination of the
protein content, the
calmodulin activity of the homogenized samples was then measured using a
calmodulin-sensitive
phosphodiesterase enzyme bioassay. In normal skin,
calmodulin activity was 1.29 +/- 0.35 micrograms
calmodulin mg-1 epidermal
protein (mean +/- SEM, n = 12 volunteers) compared to 7.88 +/- 1.59 micrograms
calmodulin mg-1 epidermal
protein for plaque (n = 16 patients) and 10.19 +/- 2.35 micrograms
calmodulin mg-1 epidermal
protein for the uninvolved skin of 12 of these patients. The levels of biologically active
calmodulin were therefore elevated in both plaque and uninvolved epidermis of patients with
psoriasis compared to epidermis from normal volunteers. These results suggest that an abnormality in the regulation of
calmodulin activity may be involved in the pathogenesis of
psoriasis.