[Distribution and motion of calphobindin in the human body]

CPB is a placental Ca2(+)-phospholipid binding protein, with a molecular weight of approximately 35,000, that shows about 50% homology with lipocortin. CPB exerts inhibitory activities on blood coagulation and phospholipase A2. The purpose of this study was to determine the distribution of CPB in various human body fluids by ELISA and its histological localization by immunohistochemical methods. The results obtained are as follows: a. Normal human plasma contained approximately 10 ng/ml of CPB. The concentrations of CPB in ascites obtained from ovarian cancer and gastro-intestinal cancer were 495.4 +/- 1,060.9 ng/ml and 713.0 +/- 622.2 ng/ml, respectively. Seminal fluid contained an extremely high level of CPB (9,010 +/- 4,010 ng/ml). b. CPB was demonstrated on syncytiotrophoblasts of the placenta. It probably functions as an anticoagulant in maintaining intervillous circulation. c. CPB was demonstrated on alveolar phagocytes in the lung and splenocytes in the spleen, indicating that CPB is related to macrophages. d. CPB was observed on islets of Langerhans and paraganglia cells of the adrenal medulla, suggesting a role of exocytosis as in calelectrins. Epithelial cells of the prostate gland, the interlobular bile duct, the pancreatic duct and the urinary tubule were also stained, indicating that CPB functions in preventing intracanalicular fibrin formation by inhibiting coagulation. e. CPB was observed on mesothelial cells in ascites, explaining the high level of CPB in ascites. f. CPB was present in the intracellular matrix of the endometrium, and is released into the extracellular fluid by cell destruction. g. The intracellular CPB content was not influenced by progesterone or dexamethasone, suggesting that the function of CPB is different from that of lipocortin.