Kelton J G, Denomme G, Walker C, Horsewood P, Gauldie J
J Immunoassay. 1983;4(1):65-82. doi: 10.1080/15321818308057000.
The amount of IgG on the surface of washed platelets from healthy individuals varies according to the assay used. An immunoradiometric assay (IRMA) for IgG was developed, validated and used to measure platelet associated IgG. The platelet-associated IgG (PAIgG) on washed platelets was allowed to react with excess 125I-labelled anti-IgG. The unbound 125I-anti-IgG was then quantitated by the addition of sepharose beads to which IgG had been covalently bound. The 125I-anti-IgG/IgG-beads were separated from the platelet suspension by passage across a density gradient. The mean amount of IgG present on washed platelets from healthy individuals was 0.8 fg IgG/platelet, or approximately 4,000 molecules of IgG per cell. Inverse Scatchard analysis confirmed the validity of the assay calibration and identical results were obtained when five different anti-IgG antibodies were used. The specific binding of 125I-anti-IgG to platelet-bound IgG was complete by 30 min, but non-specific binding of radioactivity continued thereafter. This non-specific binding occurred not only with anti-IgG but with all antibodies tested and could give elevated estimates of PAIgG in direct binding assays.
健康个体洗涤血小板表面的IgG量因所采用的检测方法而异。开发、验证了一种用于检测IgG的免疫放射分析（IRMA）并用于测量血小板相关IgG。使洗涤血小板上的血小板相关IgG（PAIgG）与过量的125I标记抗IgG反应。然后通过加入已共价结合IgG的琼脂糖珠来定量未结合的125I抗IgG。通过密度梯度将125I抗IgG/IgG珠与血小板悬液分离。健康个体洗涤血小板上存在的IgG平均量为0.8 fg IgG/血小板，即每个细胞约4000个IgG分子。反向Scatchard分析证实了检测校准的有效性，并且当使用五种不同的抗IgG抗体时获得了相同的结果。125I抗IgG与血小板结合IgG的特异性结合在30分钟时完成，但此后放射性的非特异性结合仍在继续。这种非特异性结合不仅发生在抗IgG上，也发生在所有测试的抗体上，并且在直接结合测定中可能导致PAIgG的估计值升高。
