Biologically active calmodulin levels are elevated in both involved and uninvolved epidermis in psoriasis.

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.