Immunohistochemical localization of calmodulin in normal and psoriatic epidermis.

Abstract

Calmodulin (CAM) is a major Ca2+-binding intracellular protein of eukaryotic cells. As well as having other functions, it has been related to proliferation, cell cycle, differentiation, and spatial arrangement of intermediate filaments (for overview see [2]). CaM gained particular attention in psoriasis research with publication of the first report on raised activity in psoriatic plaques, by van de Kerkhof and van Erp in 1983 [1, 3, 7 9 , 11]. Nevertheless, no information is available about the intraepidermal distribution of this protein in psoriatic skin. As far as we know, there is only one recent report of immunohistochemical CaM detection on paraffin sections of normal human skin, suggesting a homogeneous distribution in all living cell layers [5]. Therefore, using histochemical techniques, we investigated epidermal CaM in normal and psoriatic skin. Skin biopsy specimens were obtained from healthy volunteers, and lesional and nonlesional psoriatic skin from patients after local analgesia. The tissues were snapfrozen in liquid nitrogen and processed to unfixed frozen sections of 4-1am thickness. Potyclonal anti-CaM was raised in rabbits, as previously described [10]. The working dilution was 1 : 100 in phosphate-buffered saline (PBS), pH 7.4, supplemented with 0.2% bovine serum albumin and 0.5 ml Tween 20 per liter. Tissue sections were treated with PBS-Tween 20 containing 5% goat serum for 20 min at room temperature and washed twice. Anti-CaM was added