Pathophysiological significance of autoantibody to liver plasma membrane-bound cytoskeleton-related proteins in liver diseases.

本研究发现了一种从未被描述过的钙调素（CaM）自身抗体，并着重阐明了这种自身抗体的临床和病理生理意义。用酶联免疫吸附试验（ELISA）检测抗钙调素自身抗体（CaM抗体）。免疫球蛋白结合牛脑钙调素固定到免疫板测定使用HRP标记的抗人IgG，IgM和伊加。用牛脑钙调素或人红细胞钙调素吸收血清可降低钙调素抗体，而用肌动蛋白、tropnin C或DNA吸收血清则不降低钙调素抗体。免疫印迹法也证实了CaM抗体的存在。胶原性疾病和慢性肝病患者血清中均检测到IgG类抗体，而慢性肝病患者血清中IgM类抗体的检出率高于胶原性疾病患者。在某些血清样品中，游离Ca^++存在时的抗体滴度高于游离Ca^++不存在时的抗体滴度，提示它们识别CaM的构象。用钙调素结合的琼脂糖柱，我们发现有三种类型的抗体：结合钙调素的抗体，钙^<++>-游离钙调素的抗体和这两种抗体。CaM抗体抑制磷酸二酯酶活性。但CaM抗体是否参与肝细胞损伤尚需进一步研究。

In this study, we found the autoantibody to calmodulin (CaM) which had never been described, and concentrated on clarification of clinical and pathophysiological significance of this autoantibody. The autoantibody to CaM (CaM antibody) was assayed by enzyme-linked immunosorbent assay (ELISA). Immunoglobulin bound to bovine brain CaM fixed to immunoplate was determined using HRP-conjugated antihuman IgG, IgM ad IgA. CaM antibody was decreased by absorption of serum with bovine brain CaM or human erythrocyte CaM, not with actin, tropnin C or DNA. The presence of CaM antiobody was also confirmed by immunoblotting method. IgG class antibody was found in the sera from the patients with collagen diseases as well as those with chronic liver diseases, whereas IgM class antiobody was detected more frequently in the pationts with chronic liver diseases than in those with collagen diseases, In some serum samples, the antibody titres were higher in the presence of free Ca^<++> than in its absence, suggesting that they recognized conformations of CaM. Using CaM-conjugated agarose column, we found that there were three types of antibody : antibodies that bound to Ca^<++>-bound CaM, Ca^<++>-free CaM and both of these. CaM antiobody inhibited phosphodiesterase activity. However it remained for future study whether CaM antibody was involved in the liver cell injury or not.