Uemura K, Loomes L M, Childs R A, Feizi T
Section of Glycoconjugate Research, Medical Research Council Clinical Research Centre, Harrow, Middlesex, United Kingdom.
Infect Immun. 1988 Dec;56(12):3015-20. doi: 10.1128/iai.56.12.3015-3020.1988.
The aim of this study was to investigate whether I antigen occurs in association with Mycoplasma pneumoniae in a form that may be immunogenic during natural infection or experimental immunization. I antigen activity was detected by radioimmunoassay in suspensions of M. pneumoniae MY11965 and in the soluble phase of mycoplasma lysates prepared with Triton X-100. There was evidence for the occurrence of I antigen in at least two macromolecular forms. The first form partitioned in the lipid phase following chloroform-methanol extraction and chromatographed on thin-layer chromatograms as a ceramide decasaccharide. The second form was associated with the residue after lipid extraction and was solubilized by treatment with sodium dodecyl sulfate or pepsin; this component was tentatively designated a glycoprotein or polysaccharide and was not investigated further. In a lipid extract from mycoplasmas that had been surface labeled by the galactose oxidase-NaB3H4 method, two 3H-labeled glycolipids were detected as minor components which chromatographed on thin-layer chromatograms in the region of an authentic I-active ceramide decasaccharide. However, no significant radioactivity was incorporated into glycolipids after metabolic labeling with [3H]glucosamine. These observations suggested that the mycoplasmas contained surface-associated glycolipids with I antigen activity that were of exogenous origin. This was supported by the observations that horse, rabbit, and fetal calf sera contained I antigen activity and that the I antigen activity in M. pneumoniae cultures reflected the levels found in the sera included in the culture media. From rabbit serum, which expressed the highest antigen activity, an I-active glycolipid was isolated that chromatographed as a ceramide decasaccharide. I-active substances passively adsorbed onto M. pneumoniae are potentially immunogenic. However, we consider these unlikely to be the main stimulus for autoantibody production in natural infection, since the autoantibodies elicited are restricted to the I carbohydrate antigen and there is a lack of antibodies to other glycolipids that may be adsorbed from serous and cellular components of the host tissues. In our view, the more likely stimulus is the specific complex formed between the mycoplasma and the sialo-oligosaccharide receptors of the Ii antigen type, as suggested previously.
本研究的目的是调查I抗原是否以在自然感染或实验性免疫期间可能具有免疫原性的形式与肺炎支原体相关联。通过放射免疫测定法在肺炎支原体MY11965的悬浮液以及用Triton X-100制备的支原体裂解物的可溶相中检测到I抗原活性。有证据表明I抗原至少以两种大分子形式存在。第一种形式在氯仿 - 甲醇提取后分配在脂质相中，并在薄层色谱图上作为神经酰胺十糖进行色谱分析。第二种形式与脂质提取后的残渣相关，并且通过用十二烷基硫酸钠或胃蛋白酶处理而溶解；该成分暂定为糖蛋白或多糖，未作进一步研究。在用半乳糖氧化酶 - NaB3H4方法进行表面标记的支原体脂质提取物中，检测到两种3H标记的糖脂作为次要成分，它们在薄层色谱图上在真实的I活性神经酰胺十糖区域进行色谱分析。然而，在用[3H]葡糖胺进行代谢标记后，没有明显的放射性掺入糖脂中。这些观察结果表明支原体含有具有I抗原活性的表面相关糖脂，其来源是外源性的。马、兔和胎牛血清含有I抗原活性以及肺炎支原体培养物中的I抗原活性反映了培养基中所含血清中的水平，这些观察结果支持了这一点。从具有最高抗原活性的兔血清中分离出一种I活性糖脂，其色谱分析为神经酰胺十糖。被动吸附到肺炎支原体上的I活性物质可能具有免疫原性。然而，我们认为这些不太可能是自然感染中自身抗体产生的主要刺激因素，因为引发的自身抗体仅限于I碳水化合物抗原，并且缺乏针对可能从宿主组织的浆液和细胞成分吸附的其他糖脂的抗体。我们认为，更可能的刺激因素是如先前所建议的支原体与Ii抗原类型的唾液酸寡糖受体之间形成的特异性复合物。
