Yeni P, Harpin M L, Habibi B, Billecocq A, Morelec M J, Clauvel J P, Danon F, Baumann N, Brouet J C
J Clin Invest. 1984 Oct;74(4):1165-72. doi: 10.1172/JCI111525.
The mechanism of cryoprecipitation of a monoclonal IgM kappa cryoglobulin (Mou) with a cold agglutinin activity of Pr2 specificity has been studied. By immunodiffusion this cryoglobulin reacted (by its Fab' fragment) with micellar GM3, a ganglioside bearing the Pr2 antigenic determinant. In contrast to previous reports that indicated a possible temperature dependent self-association of IgM molecules via an immunological interaction leading to cold precipitation, we could not detect any affinity of this cryoglobulin for IgM when we used passive hemagglutination or an indirect enzyme-linked immunosorbent assay (ELISA). However, a GM3-like ganglioside could be extracted, by drastic methods, from the cryoglobulin studied at 22 degrees C, whereas no GM3 was extracted from two control cryoglobulins. Some minor gangliosides (representing less than 25% of total amount of bound gangliosides) were also extracted from Mou cryoglobulin and these gangliosides were shown to crossreact with GM3, as they specifically bind to Mou cryoglobulin by ELISA. After cryoprecipitation the serum still contained a monoclonal anti-Pr2 IgM kappa. A GM3-like ganglioside could be extracted from this purified IgM, and cryoprecipitability could be induced by the addition of a minute amount of micellar GM3. These results suggest that Mou cryoglobulin circulates as an immune complex and that cryoprecipitation may depend on unique IgM-GM3 (or IgM-GM3 cross-reacting gangliosides) complexes.
对具有Pr2特异性冷凝集素活性的单克隆IgM κ型冷球蛋白（Mou）的冷沉淀机制进行了研究。通过免疫扩散，这种冷球蛋白（通过其Fab'片段）与胶束状GM3发生反应，GM3是一种带有Pr2抗原决定簇的神经节苷脂。与之前报道指出IgM分子可能通过免疫相互作用发生温度依赖性自缔合导致冷沉淀不同，当我们使用被动血凝试验或间接酶联免疫吸附测定（ELISA）时，未检测到这种冷球蛋白与IgM有任何亲和力。然而，通过剧烈方法，可以从22℃下研究的冷球蛋白中提取出一种类似GM3的神经节苷脂，而从两种对照冷球蛋白中未提取到GM3。还从Mou冷球蛋白中提取了一些少量的神经节苷脂（占结合神经节苷脂总量的不到25%），并且这些神经节苷脂显示与GM3发生交叉反应，因为它们通过ELISA特异性结合Mou冷球蛋白。冷沉淀后，血清中仍含有单克隆抗Pr2 IgM κ。可以从这种纯化的IgM中提取出一种类似GM3的神经节苷脂，并且通过添加微量的胶束状GM3可以诱导冷沉淀性。这些结果表明，Mou冷球蛋白以免疫复合物形式循环，并且冷沉淀可能取决于独特的IgM-GM3（或IgM-GM3交叉反应神经节苷脂）复合物。
