Lim P L, Choy W F
Department of Microbiology, University of Hong Kong.
J Immunol Methods. 1988 Dec 9;115(2):269-74. doi: 10.1016/0022-1759(88)90297-9.
A spectrophotometer set at a wavelength of 400 nm was used to read reaction mixtures containing a 0.01% suspension of antibody-sensitized latex particles and different amounts of soluble antigen, after incubation in tubes for 30 min. The antigen used was Salmonella typhi lipopolysaccharide, and the antibody was an O-9-specific monoclonal antibody. Agglutination was indicated by a fall in the turbidimetric measurement compared to control, unagglutinated latex. It was observed that agglutination increased with increasing concentrations of antigen to a maximum at 0.25-1.0 micrograms/ml, after which, the amount of agglutination decreased at a similar rate as far as 1 mg/ml of antigen, when no agglutination occurred at all. Thus, a bi-symmetrical curve was obtained, suggestive of a precipitation reaction. At the 'equivalence point', the turbidity of the reaction mixture compared to control fell from OD400 1.1 to OD400 0.3. A similar inhibition of reaction at 'antigen excess' was observed visually in the reaction mixtures. Conventional slide tests performed in parallel could also be inhibited, but at higher antigen levels. Inhibition could be achieved with a commercially available latex used for the detection of Neisseria meningitidis antigen.
将反应混合物置于试管中孵育30分钟后，使用波长设定为400 nm的分光光度计读取含有0.01%抗体致敏乳胶颗粒悬浮液和不同量可溶性抗原的反应混合物。所用抗原为伤寒沙门氏菌脂多糖，抗体为O-9特异性单克隆抗体。与未凝集的对照乳胶相比，比浊法测量值下降表明发生了凝集。观察到，随着抗原浓度的增加，凝集增加，在0.25 - 1.0微克/毫升时达到最大值，此后，凝集量以相似的速率下降，直至1毫克/毫升抗原时完全不发生凝集。因此，得到了一条双对称曲线，提示发生了沉淀反应。在“等价点”，反应混合物与对照相比的浊度从OD400 1.1降至OD400 0.3。在反应混合物中肉眼也观察到在“抗原过量”时反应受到类似抑制。同时进行的传统玻片试验也可被抑制，但所需抗原水平更高。使用用于检测脑膜炎奈瑟菌抗原的市售乳胶可实现抑制。
