van Es L A, Knutson D W, Kayser B S, Glassock R J
Immunology. 1979 Jun;37(2):485-93.
Soluble oligovalent antigen--antibody complexes were prepared and analysed by ultracentrifugation in order to study the effect of the combining ratio, antigen valence and concentration upon the size and molecular composition of the composition of the complexes. Fluorescein (F) conjugates of rabbit serum albumin (RSA) and thyroglobulin (RTg) were combined with high affinity rabbit anti-F antibodies to form soluble complexes. The effect of the combining ratio paralleled findings in precipitating systems in that the largest soluble complexes were found at equimolarity and mild molar antibody excess. Tetravalent antigen formed precipitates at combining ratios near equimolarity, whereas trivalent antigens failed to precipitate at similar concentrations. Complexes prepared near equimolarity were most sensitive to changes in concentration, higher concentrations leading to larger complexes. The Ab/Ag ratios of different-size complexes in the same preparation were remarkably similar. This ratio was dependent on the antibody--antigen combining ratio, was limited by antigen valence and was not affected by concentration differences. The data support the hypothesis that soluble complexes are formed in two steps. First, antigen and antibody combine to form subunits whose Ab/Ag ratio is determined by the combining ratio and antigen valence. These subunits then combine to form larger complexes in a manner analogous to polymerization.
制备了可溶性多价抗原 - 抗体复合物，并通过超速离心进行分析，以研究结合比例、抗原价和浓度对复合物大小和分子组成的影响。兔血清白蛋白（RSA）和甲状腺球蛋白（RTg）的荧光素（F）缀合物与高亲和力兔抗F抗体结合形成可溶性复合物。结合比例的影响与沉淀系统中的发现相似，即在等摩尔浓度和轻度摩尔抗体过量时发现最大的可溶性复合物。四价抗原在接近等摩尔浓度的结合比例下形成沉淀，而三价抗原在相似浓度下未能沉淀。在接近等摩尔浓度时制备的复合物对浓度变化最敏感，较高浓度导致形成更大的复合物。同一制剂中不同大小复合物的Ab/Ag比值非常相似。该比值取决于抗体 - 抗原结合比例，受抗原价限制，不受浓度差异影响。数据支持可溶性复合物分两步形成的假设。首先，抗原和抗体结合形成亚基，其Ab/Ag比值由结合比例和抗原价决定。然后这些亚基以类似于聚合的方式结合形成更大的复合物。
