Ulanova M, Hahn-Zoric M, Lau Y L, Lucas A, Hanson L A
Department of Clinical Immunology, University of Göteborg, Sweden.
Clin Exp Immunol. 1996 Sep;105(3):422-8. doi: 10.1046/j.1365-2249.1996.d01-788.x.
The Chinese population in Hong Kong has a low incidence of invasive Haemophilus influenzae type b(Hib) disease, as well as carriage of the microorganism. Likely stimuli for the natural antibodies to Hib, which might protect against Hib infection, are cross-reactive antigens of bacteria like Escherichia coli K 100. Our aim was to determine the isotype and idiotype distribution and cross-reactivity of natural antibodies against Hib capsular polysaccharide (CP) in healthy Hong Kong Chinese. Titration of 20 sera by ELISA showed IgG antibodies reacting with Hib CP in all individuals. The antibodies were mainly IgG2, and their avidity index ranged widely. Isoelectric focusing (IEF) combined with immunoblotting showed patterns of IgG2 antibody clones against the CP of Hib and E. coli K 100 which were similar in 10 cases. Absorption with Hib CP only eliminated some bands in two sera. Absorption with K 100 CP did not remove any anti-Hib CP bands. In three sera additional clones of antibodies reacting to K 100 CP only, disappeared after absorption with this CP. Spectrotypic analyses of IgG antibodies reacting with anti-Hib idiotype 1 (Id-1) revealed stronger IEF patterns with bands in differing locations compared with anti-Hib CP antibodies. The strong reactivity of serum IgG, IgA and IgM antibodies with monoclonal anti-Hib Id-1 was confirmed by ELISA. This reactivity was not abolished after absorption of the sera with either Hib CP, or K 100 CP. The data indicate a high prevalence of Id-1 among Hong Kong Chinese. However, only one individual had Id-1 antibodies specific for Hib CP, judging from absorption experiments. Others had much lower activity of Id-1 anti-Hib CP antibodies compared with the total IgG Id-1, suggesting that Hong Kong subjects have Id-1-positive antibodies in their serum which are not specific for Hib CP. This is consistent with the nature of Id-1, which is a marker of A2VL region usage rather than a marker of a Hib CP paratope. We suggest that natural antibodies reacting with Hib CP in healthy Hong Kong Chinese are the product of exposure to some cross-reactive antigen(s), different from both Hib and E. coli K 100 CP.
香港的中国人群侵袭性b型流感嗜血杆菌（Hib）疾病以及该微生物的携带率较低。可能刺激针对Hib的天然抗体（可能预防Hib感染）的是大肠杆菌K100等细菌的交叉反应抗原。我们的目的是确定健康香港中国人中针对Hib荚膜多糖（CP）的天然抗体的同种型和独特型分布以及交叉反应性。通过ELISA对20份血清进行滴定显示，所有个体中均有与Hib CP反应的IgG抗体。这些抗体主要为IgG2，其亲和力指数范围广泛。等电聚焦（IEF）结合免疫印迹显示，针对Hib和大肠杆菌K100的CP的IgG2抗体克隆模式在10例中相似。用Hib CP吸收仅消除了两份血清中的一些条带。用K100 CP吸收并未去除任何抗Hib CP条带。在三份血清中，仅与K100 CP反应的额外抗体克隆在用该CP吸收后消失。对与抗Hib独特型1（Id-1）反应的IgG抗体进行光谱分析显示，与抗Hib CP抗体相比，IEF模式更强，条带位置不同。ELISA证实血清IgG、IgA和IgM抗体与单克隆抗Hib Id-1有强烈反应。在用Hib CP或K100 CP吸收血清后，这种反应并未消除。数据表明Id-1在香港中国人中普遍存在。然而，从吸收实验判断，只有一名个体具有针对Hib CP的Id-1抗体。与总IgG Id-1相比，其他人的Id-1抗Hib CP抗体活性要低得多，这表明香港受试者血清中有Id-1阳性抗体，但并非针对Hib CP。这与Id-1的性质一致，Id-1是A2VL区域使用的标志物，而非Hib CP互补位的标志物。我们认为，健康香港中国人中与Hib CP反应的天然抗体是接触某些与Hib和大肠杆菌K100 CP均不同的交叉反应抗原的产物。
