Baatrup G, Svehag S E, Jensenius J C
Scand J Immunol. 1986 Apr;23(4):397-406. doi: 10.1111/j.1365-3083.1986.tb03071.x.
The interaction between immune aggregates and complement (C) was investigated. Solid-phase immune aggregates were prepared by coating microwells with heat-aggregated bovine serum albumin (BSA) followed by rabbit anti-BSA antibody. The immune aggregates were reacted with human serum or citrated plasma at 37 degrees C. The binding of C3 components was investigated with biotinylated F(ab')2 antibodies to C3c and C3d and avidin-coupled alkaline phosphatase. The form of the incorporated C3, whether C3b-iC3b or C3dg, can be deduced from the response with these two antibodies. The maximal binding of C3b-iC3b to the immune aggregates was observed within 5 min of incubation with serum or citrated plasma. The conversion to C3dg was evident by a decrease in bound anti-C3c concomitant with increasing anti-C3d reactivity within about 10 min of incubation. When the classical C pathway activation was inhibited, the binding of C3b-iC3b was delayed by 20-30 min, whereas stopping of the alternative pathway did not influence the initial kinetics of the reaction. The addition of human red blood cells had no measurable influence on the degradation of bound C3b-iC3b. 125I-labelled anti-BSA antibody bound to the solid-phase BSA was not released during the C3 incorporation. The incorporation of C3b into the immune aggregates was mediated equally well by serum and by citrated plasma. The incorporation of C3b-iC3b into immune complexes (IC) is thought to be responsible for the C-mediated solubilization (CMS) of IC. Citrated plasma, however, exerted no CMS capacity when measured by a radiometric assay. The CMS capacity of serum was inhibited by citrate, but could then be restored by adding Ca2+ and Mg2+, whereas no CMS could be demonstrated with citrated plasma to which divalent metal ions were added.
研究了免疫聚集体与补体（C）之间的相互作用。通过用热聚集的牛血清白蛋白（BSA）包被微孔，然后加入兔抗BSA抗体来制备固相免疫聚集体。免疫聚集体在37℃下与人血清或枸橼酸盐血浆反应。用生物素化的抗C3c和C3d的F(ab')2抗体以及抗生物素蛋白偶联的碱性磷酸酶研究C3成分的结合情况。结合的C3的形式，无论是C3b-iC3b还是C3dg，可以通过这两种抗体的反应来推断。在与血清或枸橼酸盐血浆孵育5分钟内观察到C3b-iC3b与免疫聚集体的最大结合。在孵育约10分钟内，随着抗C3d反应性增加，结合的抗C3c减少，向C3dg的转化变得明显。当经典C途径激活被抑制时，C3b-iC3b的结合延迟20 - 30分钟，而替代途径的阻断不影响反应的初始动力学。加入人红细胞对结合的C3b-iC3b的降解没有可测量的影响。在C3掺入过程中，与固相BSA结合的125I标记的抗BSA抗体没有释放。血清和枸橼酸盐血浆介导C3b掺入免疫聚集体的效果相同。C3b-iC3b掺入免疫复合物（IC）被认为是IC的补体介导溶解（CMS）的原因。然而，通过放射性测定法测量时，枸橼酸盐血浆没有CMS能力。血清的CMS能力被枸橼酸盐抑制，但随后可以通过添加Ca2+和Mg2+恢复，而添加二价金属离子的枸橼酸盐血浆未显示出CMS能力。
