Joiner K A, Goldman R C, Hammer C H, Leive L, Frank M M
J Immunol. 1983 Nov;131(5):2563-9.
The mechanism of antibody-dependent complement-(C) mediated killing of Escherichia coli 0111B4, strain 12015 (12015), was examined. 12015 was resistant to serum killing when incubated in hypogammaglobulinemic serum (H gamma S) or pooled normal human serum (NHS) that had been previously adsorbed to remove specific antibody (Abs NHS). Presensitization with immune rabbit serum or purified immune rabbit IgG resulted in 1 to 3 log killing when 5 X 10(8) colony forming units (CFU)/ml were incubated in 10 to 40% Abs NHS. Binding of 125I-C3 and 131I-C9 to the bacterial surface of the presensitized and the nonpresensitized strain was quantitated when these organisms were incubated in 10, 20, and 40% Abs NHS. Stable binding of up to 3.0 X 10(5) molecules of C3 and 8.0 X 10(4) molecules of C9 to presensitized and nonpresensitized isolates occurred in the highest concentration of serum, but there was no killing without presensitization. Similar results were found when Abs NHS was chelated with ethylene bis glycoltetraacetic acid containing 2 mM MgCl2 (Mg EGTA) to block classical pathway activation, indicating that antibody mediated the bactericidal reaction through the alternative pathway. Deposition of C3 and C9 and killing of 120 15 in 10% Abs NHS or 10% H gamma S was measured after presensitization with increasing amounts of IgG, F(ab')2, or Fab'. There was a dose-dependent increase in C3 deposition and killing, but only minimal change in C9 binding when 1.0 X 10(3) to 3.2 X 10(4) IgG or F(ab')2/CFU were bound to the bacterial surface. In contrast, there was no increase in C3 or C9 binding and no bacterial killing when 1 X 10(3) to 3.4 X 10(4) molecules Fab'/CFU were bound to the bacterial surface. These experiments show that immune IgG and F(ab')2 can mediate killing of E. Coli 0111B4 by the alternative pathway without changing the extent of terminal C component attachment to the bacterial surface.
研究了抗体依赖性补体（C）介导的对大肠杆菌0111B4菌株12015（12015）的杀伤机制。当12015在低丙种球蛋白血症血清（HγS）或先前已吸附去除特异性抗体（Abs NHS）的混合正常人血清（NHS）中孵育时，它对血清杀伤具有抗性。当5×10⁸菌落形成单位（CFU）/ml在10%至40%的Abs NHS中孵育时，用免疫兔血清或纯化的免疫兔IgG进行预致敏会导致1至3个对数级的杀伤。当这些生物体在10%、20%和40%的Abs NHS中孵育时，对预致敏和未预致敏菌株的细菌表面上¹²⁵I - C3和¹³¹I - C9的结合进行了定量。在最高血清浓度下，高达3.0×10⁵个C3分子和8.0×10⁴个C9分子稳定结合到预致敏和未预致敏的分离株上，但未预致敏时没有杀伤作用。当用含有2 mM MgCl₂的乙二醇双四乙酸（Mg EGTA）螯合Abs NHS以阻断经典途径激活时，发现了类似的结果，这表明抗体通过替代途径介导杀菌反应。在用增加量的IgG、F(ab')₂或Fab'进行预致敏后，测量了10% Abs NHS或10% HγS中C3和C9的沉积以及12015的杀伤情况。当1.0×10³至3.2×10⁴个IgG或F(ab')₂/CFU结合到细菌表面时，C3沉积和杀伤呈剂量依赖性增加，但C9结合仅有微小变化。相比之下，当1×10³至3.4×10⁴个Fab'/CFU结合到细菌表面时，C3或C9结合没有增加，也没有细菌杀伤。这些实验表明，免疫IgG和F(ab')₂可以通过替代途径介导对大肠杆菌0111B4的杀伤，而不会改变末端补体成分附着到细菌表面的程度。
