Division of Immunology, Boston Children's Hospital, Boston, MA 02115, USA.
J Clin Immunol. 2013 May;33(4):847-56. doi: 10.1007/s10875-013-9870-9. Epub 2013 Feb 3.
The quality of an antibody response is determined by both the concentration and the strength of antigen-binding, or avidity, of the antibodies produced. Currently, only antibody concentration is routinely evaluated in the clinical assessment of humoral immunity. Here we studied correlations of avidities and concentrations of antibodies to pneumococcal polysaccharides with immunologic and clinical characteristics of patients with recurrent infections.
We measured concentration and avidity of antibodies to 12 pneumococcal serotypes in 78 children aged 0.6-18 years with recurrent bacterial respiratory infections, and in 80 individuals who were being tested for peanut allergy, ages 0.4-15 years, serving as a comparison group. Avidity was assessed by measuring antibody binding in the presence of thiocyanate.
Antibody concentrations and avidities correlated positively for very few types contained in the conjugated pneumococcal vaccine (PCV7) in both patients and controls with some dependence on age; there were even fewer correlations for non-PCV7 types. Antibody concentrations and avidities negatively correlated with age for most of the PCV7 types. There was no consistent correlation of total IgG or IgG subclasses with either concentrations or avidities. Overall, antibody concentrations were higher and avidities were lower in patients compared to controls. Patients requiring chronic antibiotic use tended to have higher antibody concentrations and lower avidities for most serotypes than patients who did not. We identified several patients having many infections with apparent good antibody concentrations with low avidity for many types.
Antibody concentration and avidity correlate with patient clinical characteristics and distinguish patients from controls. Measurement of antibody avidity may provide another dimension for the clinical assessment of pneumococcal polysaccharide antibody response.
抗体反应的质量取决于产生的抗体的浓度和抗原结合的强度，即亲和力。目前，在对体液免疫的临床评估中，仅常规评估抗体浓度。在这里，我们研究了对肺炎球菌多糖的抗体亲和力和浓度与复发性感染患者的免疫和临床特征的相关性。
我们测量了 78 名 0.6-18 岁复发性细菌性呼吸道感染儿童和 80 名 0.4-15 岁正在接受花生过敏测试的个体对 12 种肺炎球菌血清型的抗体浓度和亲和力，对照组。通过在硫氰酸盐存在下测量抗体结合来评估亲和力。
在患者和对照组中，很少有与结合肺炎球菌疫苗（PCV7）相关的类型的抗体浓度和亲和力呈正相关，并且存在一定程度的年龄依赖性；对于非 PCV7 类型，相关性更少。对于大多数 PCV7 类型，抗体浓度和亲和力随年龄增长而呈负相关。总 IgG 或 IgG 亚类与浓度或亲和力均无一致相关性。总的来说，与对照组相比，患者的抗体浓度较高，亲和力较低。与未使用慢性抗生素的患者相比，需要长期使用抗生素的患者大多数血清型的抗体浓度较高，亲和力较低。我们发现了一些患者，尽管有许多感染，但对许多类型的抗体亲和力低，但其抗体浓度似乎很好。
抗体浓度和亲和力与患者的临床特征相关，并将患者与对照组区分开来。抗体亲和力的测量可能为肺炎球菌多糖抗体反应的临床评估提供另一个维度。
