Perlmann H, Perlmann P, Moretta L, Rönnholm M
Scand J Immunol. 1981 Jul;14(1):47-60. doi: 10.1111/j.1365-3083.1981.tb00183.x.
IgM antibodies have previously been reported to either inhibit or induce antibody-dependent lymphocyte cytotoxicity (ADCC). Here we show that human lymphocytes lyse bovine erythrocytes (Eb) in the presence of either IgM of IgG anti-Eb from rabbits. Seven out of 20 IgM preparations (Sephadex G-200) were ADCC-active. IgG-dependent ADCC was inhibited by human IgG but not by IgM. In contrast, IgM ADCC was inhibited by both IgG and IgM. The effector cells in IgM ADCC were a subpopulation of lymphocytes with distinct Fc receptors for both IgG and IgM. Most of them also had sheep erythrocyte receptors. Extensive purification of the ADCC-active IgM antibody preparations indicated that very small amounts of contaminating IgG anti-Eb were responsible for ADCC induction. When purified and ADCC-inactive IgM antibodies were mixed with suboptimal concentrations of IgG antibodies, a strong enhancement of ADCC was found. To achieve enhancement, the two antibody isotypes had to be present on the surface of the same target cells, and the IgM effect was not due to the release of soluble ADCC-enhancing factors. Thus, in this system, IgM antibodies are not capable of inducing ADCC on their own. However, they enhance ADCC by improving the contactual interaction between target cells and a special subset of effector cells.
此前有报道称，IgM抗体既能抑制也能诱导抗体依赖性淋巴细胞细胞毒性（ADCC）。在此我们发现，在存在兔抗牛红细胞（Eb）的IgM或IgG的情况下，人淋巴细胞可裂解牛红细胞。20种IgM制剂（葡聚糖凝胶G - 200）中有7种具有ADCC活性。IgG依赖性ADCC受到人IgG的抑制，但不受IgM的抑制。相比之下，IgM介导的ADCC受到IgG和IgM两者的抑制。IgM介导的ADCC中的效应细胞是淋巴细胞的一个亚群，其具有针对IgG和IgM的独特Fc受体。它们中的大多数也有绵羊红细胞受体。对具有ADCC活性的IgM抗体制剂进行广泛纯化表明，极少量的污染性IgG抗Eb导致了ADCC的诱导。当将纯化的且无ADCC活性的IgM抗体与次优浓度的IgG抗体混合时，发现ADCC有显著增强。为实现增强效果，两种抗体亚型必须存在于同一靶细胞表面，且IgM的作用并非由于可溶性ADCC增强因子的释放。因此，在这个系统中，IgM抗体自身不能诱导ADCC。然而，它们通过改善靶细胞与效应细胞的一个特殊亚群之间的接触性相互作用来增强ADCC。
