Johnston R B, Klemperer M R, Alper C A, Rosen F S
J Exp Med. 1969 Jun 1;129(6):1275-90. doi: 10.1084/jem.129.6.1275.
The role of serum factors in the phagocytosis of pneumococci was studied employing a spectrophotometric assay which measures reduced nitro blue tetrazolium (NBT) dye. Dye reduction occurs within the phagocyte shortly after bacterial ingestion as measured by the phagocytic index technique and by the uptake of (125)I-pneumococci. Bacteria prepared with gammaG antibody were not phagocytosed unless a small volume of fresh normal serum was added. Using fresh sera deficient in single complement components, it was demonstrated that the first four components are necessary for optimal bacterial phagocytosis. When highly purified complement components were added to the antibody-coated pneumococci, enhancement of phagocytosis was achieved only with the sequential addition of C1, C4, C2, and C3. Evidence has been presented that human C3 bound to an immune complex exhibits peptidase activity and that this activity is essential for phagocytosis. A heat-labile, dialyzable serum cofactor which enhances C3 peptidase activity enhanced the phagocytosis of pneumococci prepared with purified complement components. A second phagocytosis-promoting cofactor, which is not a complement component, was found to be a heat-labile, 5-6S, beta pseudoglobulin. This protein may stabilize C3 peptidase activity or inhibit enzymatic inactivation of C3.
利用一种测定还原型硝基蓝四氮唑（NBT）染料的分光光度法，研究了血清因子在肺炎球菌吞噬作用中的作用。通过吞噬指数技术和（125）I标记肺炎球菌的摄取量来测定，细菌被吞噬后不久，吞噬细胞内就会发生染料还原。用γG抗体处理的细菌不会被吞噬，除非加入少量新鲜正常血清。使用缺乏单一补体成分的新鲜血清，结果表明前四种补体成分对于最佳的细菌吞噬作用是必需的。当将高度纯化的补体成分添加到抗体包被的肺炎球菌中时，只有依次添加C1、C4、C2和C3才能实现吞噬作用的增强。有证据表明，与免疫复合物结合的人C3具有肽酶活性，且该活性对于吞噬作用至关重要。一种能增强C3肽酶活性的热不稳定、可透析的血清辅助因子增强了用纯化补体成分制备的肺炎球菌的吞噬作用。发现第二种促进吞噬作用的辅助因子不是补体成分，而是一种热不稳定的5-6Sβ假球蛋白。这种蛋白质可能会稳定C3肽酶活性或抑制C3的酶促失活。
