O'Connor D T, Pandlan M R, Carlton E, Cervenka J H, Hslao R J
Department of Medicine, University of California, San Diego.
Clin Chem. 1989 Aug;35(8):1631-7.
Chromogranin A is a useful probe of neuroendocrine neoplasia in humans. Here we optimize a rapid, sensitive radioimmunoassay modification for detecting chromogranin A in humans and other species. The site of chromogranin A circulation is the acellular plasma; platelets contain no chromogranin A immunoreactivity. The immunoreactivity in plasma is stable to repeated freezing and thawing, prolonged incubation at 37 degrees C, and lyophilization. Venipuncture alone resulted in modest (+ 12%, P less than 0.03) increase in chromogranin A in plasma. Several classic neuroendocrine neoplasia-pheochromocytoma, carcinoid tumor, neuroblastoma, and (vasoactive intestinal polypeptide)oma-produce markedly increased chromogranin A in plasma. By contrast, subjects with malignant melanoma, renal cell carcinoma, and thymoma all had normal values for chromogranin A. Hypersecretion of human choriogonadotropin beta subunit from both malignant (choriocarcinoma) and normal (placenta) syncytiotrophoblast cells was unaccompanied by an increase in chromogranin A, a dissociation compatible with the lack of granular storage and release of syncytiotrophoblastic peptide hormones. Both hepatic and renal failure resulted in increased chromogranin A in plasma, with renal failure leading to concentrations otherwise seen only in neuroendocrine neoplasia. These observations refine the diagnostic specificity of chromogranin A in plasma.
嗜铬粒蛋白A是检测人类神经内分泌肿瘤的一种有用指标。在此，我们优化了一种快速、灵敏的放射免疫分析改良方法，用于检测人类及其他物种中的嗜铬粒蛋白A。嗜铬粒蛋白A在血液循环中的存在部位是无细胞血浆；血小板中不存在嗜铬粒蛋白A免疫反应性。血浆中的免疫反应性对反复冻融、在37℃长时间孵育及冻干均稳定。仅静脉穿刺就导致血浆中嗜铬粒蛋白A适度升高（+12%，P<0.03）。几种典型的神经内分泌肿瘤——嗜铬细胞瘤、类癌瘤、神经母细胞瘤和（血管活性肠肽）瘤——可使血浆中嗜铬粒蛋白A显著升高。相比之下，患有恶性黑色素瘤、肾细胞癌和胸腺瘤的患者嗜铬粒蛋白A值均正常。恶性（绒毛膜癌）和正常（胎盘）合体滋养层细胞分泌人绒毛膜促性腺激素β亚基增多时，嗜铬粒蛋白A并未升高，这种分离现象与合体滋养层肽类激素缺乏颗粒储存和释放相符。肝衰竭和肾衰竭均导致血浆中嗜铬粒蛋白A升高，肾衰竭导致的浓度水平在其他情况下仅见于神经内分泌肿瘤。这些观察结果提高了血浆中嗜铬粒蛋白A的诊断特异性。
