Biguzzi S
Eur J Immunol. 1979 Jan;9(1):52-60. doi: 10.1002/eji.1830090112.
Staphylococcal protein A (SpA) is known to bind the Fc region of IgG of most mammalians and to possess biologic activity both in vivo and in vitro, where it acts as a lymphocyte polyclonal mitogen. Its binding to the Fc gamma portion bears many features of the antibody-antigen interaction, such as the dissociation constant, lattice formation, and complement activation. Moreover, SpA seems to compete with membrane Fc receptors for IgG so that the possibility of an interaction with the same CH domain(s) of IgG can be considered. In the present study, evidence is given that anti-SpA antisera obtained from chickens and rabbits are able to inhibit EA rosette formation by normal human lymphocytes and that they are able to recognize, with immunofluorescent staining, a subpopulation of normal human peripheral blood lymphocytes (PBL) that closely resembles that of EA rosette-forming cells (RFC). Moreover, the depletion of EA RFC by means of a single gradient centrifugation is accomplished by the parallel depletion of PBL stainable by anti-SpA antisera. The relevance of these results in the hypothesis of a similarity between the combining sites of SpA and membrane Fc receptor(s) for IgG is discussed.
已知葡萄球菌蛋白A（SpA）可结合大多数哺乳动物IgG的Fc区，且在体内和体外均具有生物活性，它可作为淋巴细胞多克隆有丝分裂原。它与Fcγ部分的结合具有许多抗体 - 抗原相互作用的特征，如解离常数、晶格形成和补体激活。此外，SpA似乎与膜Fc受体竞争IgG，因此可以认为它与IgG相同的CH结构域存在相互作用的可能性。在本研究中，有证据表明从鸡和兔获得的抗SpA抗血清能够抑制正常人淋巴细胞形成EA花环，并且它们能够通过免疫荧光染色识别正常人外周血淋巴细胞（PBL）的一个亚群，该亚群与EA花环形成细胞（RFC）的亚群非常相似。此外，通过单次梯度离心去除EA RFC的同时，也会平行去除可被抗SpA抗血清染色的PBL。本文讨论了这些结果在SpA结合位点与IgG膜Fc受体之间相似性假设中的相关性。
