The interaction of group A streptococcal lipoteichoic acid (LTA) with mammalian cell membranes was studied in human platelets. The binding of LTA to platelets was platelet concentration and time dependent. Binding approached a maximum within 10 min of incubation. The bound LTA could be displaced by adding a 50-fold excess of unlabeled LTA. An association constant of 1.9 X 10(-7) M was calculated, and only one population of binding sites was detected. Immuno-ferritin labeling of LTA-treated platelets demonstrated a patchy distribution of LTA binding sites on the platelet surface. LTA inhibited collagen- and alpha1 chain-induced platelet aggregation, but not the platelet release reaction, suggesting that the LTA and collagen binding sites on human platelets are distinct. Apparently, LTA binds to platelets and interferes with collagen-induced aggregation although collagen is still able to attach to binding sites to trigger the release reaction.
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机译：在人类血小板中研究了A组链球菌脂蛋白酸（LTA）与哺乳动物细胞膜的相互作用。 LTA与血小板的结合是血小板浓度和时间依赖性。在孵育的10分钟内，结合达到最大值。结合的LTA可以通过添加50倍过量的未标记LTA来置换。计算的缔合常数为1.9 X 10（-7）M，并且仅检测到一组结合位点。 LTA处理的血小板的免疫铁蛋白标记显示血小板表面LTA结合位点的斑片状分布。 LTA抑制胶原蛋白和alpha1链诱导的血小板聚集，但不抑制血小板释放反应，这表明人血小板上的LTA和胶原蛋白结合位点是不同的。显然，LTA结合血小板并干扰胶原蛋白诱导的聚集，尽管胶原蛋白仍能够附着在结合位点上以触发释放反应。
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