Department of Molecular Medicine, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA; Division of Medical Oncology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA.
Department of Molecular Medicine, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA.
J Immunol Methods. 2021 May;492:112996. doi: 10.1016/j.jim.2021.112996. Epub 2021 Feb 11.
Dried blood spots (DBS) are routinely used in screening newborns for treatable disorders. Immunoglobulin extraction from DBS, serum or other biological fluids loaded on filter paper cards could represent a valuable method of specimen preservation in monitoring immune response against pathogens as well as vaccination efficiency. In this study using different sources including serum, and monoclonal antibodies we established parameters for antibody extraction from the filter cards to assess antibody reactivity against Helicobacter pylori, measles virus (MV) and the novel coronavirus SARS-CoV-2 antigens. We demonstrated that DBS and dried undiluted serum result in completely preserved antibody activity for immunoassays, including in virus neutralization assays against MV. Extraction efficiency was determined by IgG concentration measurements. The plaque-reduction neutralization titer 50% of dried human serum spots remained stable after more than 10-day storage - 1:359 vs. 1:345 for the corresponding frozen sample. DBSs could be used to monitor immune response to bacterial and viral antigens following natural exposure or immunization. Mice immunized with recombinant spike protein receptor-binding domain of SARS-CoV-2 developed a strong antibody response by day 14 and reached titers above 1:64,000 on day 21 following the secondary boost immunization as measured on DBS samples in antigen-mediated ELISA. Variability in IgG concentration of eluted DBS could be influenced by factors involved in sample application, extraction process and sample characteristics. Adjustment of antibody specific activity to the eluted IgG concentration can increase accuracy of the result interpretation, including in SARS-CoV-2 serological diagnostics.
干血斑（DBS）常用于筛查新生儿的可治疗疾病。从 DBS、血清或加载在滤纸条上的其他生物液体中提取免疫球蛋白，可以代表一种有价值的标本保存方法，用于监测针对病原体的免疫反应以及疫苗接种效率。在这项研究中，我们使用了不同的来源，包括血清和单克隆抗体，建立了从滤纸条中提取抗体的参数，以评估针对幽门螺杆菌、麻疹病毒（MV）和新型冠状病毒 SARS-CoV-2 抗原的抗体反应性。我们证明 DBS 和干燥未稀释的血清可完全保留免疫测定的抗体活性，包括针对 MV 的病毒中和测定。通过 IgG 浓度测量确定提取效率。干燥人血清斑的半数抑制滴度 50%在超过 10 天的储存后保持稳定-分别为 1:359 和 1:345，对于相应的冷冻样品。DBS 可用于监测自然暴露或免疫接种后针对细菌和病毒抗原的免疫反应。用 SARS-CoV-2 的重组刺突蛋白受体结合域免疫的小鼠在第 14 天产生了强烈的抗体反应，并在第二次加强免疫后的第 21 天达到了 DBS 样本中抗原介导的 ELISA 测量的滴度超过 1:64,000。洗脱 DBS 的 IgG 浓度的变异性可能受到样品应用、提取过程和样品特征中涉及的因素的影响。将抗体特异性活性调整到洗脱的 IgG 浓度可以提高结果解释的准确性，包括 SARS-CoV-2 血清学诊断。
