Oxford Vaccine Group, Department of Paediatrics, University of Oxford, Oxford, United Kingdom.
NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom.
Front Cell Infect Microbiol. 2020 Jan 17;9:459. doi: 10.3389/fcimb.2019.00459. eCollection 2019.
New diagnostic tests for the etiology of childhood pneumonia are needed. We evaluated the antibody-in-lymphocyte supernatant (ALS) assay to detect immunoglobulin (Ig) G secretion from peripheral blood mononuclear cell (PBMC) culture, as a potential diagnostic test for pneumococcal pneumonia. We enrolled 348 children with pneumonia admitted to Patan Hospital, Kathmandu, Nepal between December 2015 and September 2016. PBMCs sampled from participants were incubated for 48 h before harvesting of cell culture supernatant (ALS). We used a fluorescence-based multiplexed immunoassay to measure the concentration of IgG in ALS against five conserved pneumococcal protein antigens. Of children with pneumonia, 68 had a confirmed etiological diagnosis: 12 children had pneumococcal pneumonia (defined as blood or pleural fluid culture-confirmed; or plasma CRP concentration ≥60 mg/l and nasopharyngeal carriage of serotype 1 pneumococci), and 56 children had non-pneumococcal pneumonia. Children with non-pneumococcal pneumonia had either a bacterial pathogen isolated from blood (six children); or C-reactive protein <60 mg/l, absence of radiographic consolidation and detection of a pathogenic virus by multiplex PCR (respiratory syncytial virus, influenza viruses, or parainfluenza viruses; 23 children). Concentrations of ALS IgG to all five pneumococcal proteins were significantly higher in children with pneumococcal pneumonia than in children with non-pneumococcal pneumonia. The concentration of IgG in ALS to the best-performing antigen discriminated between children with pneumococcal and non-pneumococcal pneumonia with a sensitivity of 1.0 (95% CI 0.73-1.0), specificity of 0.66 (95% CI 0.52-0.78) and area under the receiver-operating characteristic curve (AUROCC) 0.85 (95% CI 0.75-0.94). Children with pneumococcal pneumonia were older than children with non-pneumococcal pneumonia (median 5.6 and 2.0 years, respectively, < 0.001). When the analysis was limited to children ≥2 years of age, assay of IgG ALS to pneumococcal proteins was unable to discriminate between children with pneumococcal pneumonia and non-pneumococcal pneumonia (AUROCC 0.67, 95% CI 0.47-0.88). This method detected spontaneous secretion of IgG to pneumococcal protein antigens from cultured PBMCs. However, when stratified by age group, assay of IgG in ALS to pneumococcal proteins showed limited utility as a test to discriminate between pneumococcal and non-pneumococcal pneumonia in children.
需要新的儿童肺炎病因学诊断检测方法。我们评估了抗体在淋巴细胞上清液（ALS）检测法，以检测外周血单个核细胞（PBMC）培养中免疫球蛋白（Ig）G 的分泌，作为检测肺炎球菌性肺炎的潜在诊断检测方法。我们招募了 2015 年 12 月至 2016 年 9 月期间在尼泊尔加德满都帕坦医院住院的 348 名肺炎患儿。从参与者中采集 PBMC 后，在收获细胞培养上清液（ALS）前孵育 48 小时。我们使用基于荧光的多重免疫测定法来测量 ALS 中针对五种保守的肺炎球菌蛋白抗原的 IgG 浓度。在患有肺炎的儿童中，有 68 名具有明确的病因学诊断：12 名儿童患有肺炎球菌性肺炎（定义为血液或胸腔液培养确认；或血浆 C 反应蛋白浓度≥60mg/l 和鼻咽携带血清型 1 肺炎球菌），56 名儿童患有非肺炎球菌性肺炎。患有非肺炎球菌性肺炎的儿童要么从血液中分离出细菌病原体（6 名儿童）；要么 C 反应蛋白<60mg/l，无影像学实变，并且通过多重 PCR 检测到致病性病毒（呼吸道合胞病毒、流感病毒或副流感病毒；23 名儿童）。与非肺炎球菌性肺炎患儿相比，肺炎球菌性肺炎患儿的 ALS 中针对所有五种肺炎球菌蛋白的 IgG 浓度明显更高。针对最佳表现抗原的 ALS IgG 浓度可区分肺炎球菌性和非肺炎球菌性肺炎患儿，其敏感性为 1.0（95%CI 0.73-1.0），特异性为 0.66（95%CI 0.52-0.78），受试者工作特征曲线下面积（AUROCC）为 0.85（95%CI 0.75-0.94）。患有肺炎球菌性肺炎的儿童比患有非肺炎球菌性肺炎的儿童年龄更大（中位数分别为 5.6 岁和 2.0 岁，<0.001）。当分析仅限于≥2 岁的儿童时，肺炎球菌蛋白 ALS 检测法无法区分肺炎球菌性肺炎和非肺炎球菌性肺炎患儿（AUROCC 0.67，95%CI 0.47-0.88）。该方法检测到从培养的 PBMC 中自发分泌的肺炎球菌蛋白抗原 IgG。然而，按年龄组分层时，ALS 中针对肺炎球菌蛋白的 IgG 检测作为区分儿童肺炎球菌性和非肺炎球菌性肺炎的检测方法，其应用价值有限。
