Institute for Medical Immunology, Charité University Medicine Berlin, Berlin, Germany.
Institute for Medical Immunology, Charité University Medicine Berlin, Berlin, Germany; Berlin-Brandenburg Centre for Regenerative Therapies, Berlin, Germany; Out-patients Clinic for Immunodeficiencies, Charité University Medicine Berlin, Berlin, Germany.
J Allergy Clin Immunol. 2015 Jan;135(1):198-208. doi: 10.1016/j.jaci.2014.06.022. Epub 2014 Aug 10.
The population of patients with common variable immunodeficiency (CVID) comprises a heterogeneous group of patients with different causes of hypogammaglobulinemia predisposing to recurrent infections, higher incidence of autoimmunity, and malignancy. Although memory B cells (memBcs) are key players in humoral defense and their numbers are commonly reduced in these patients, their functionality is not part of any current classification.
We established and validated a memBc enzyme-linked immunosorbent spot (ELISpot) assay that reveals the capacity of memBcs to develop into antibody-secreting cells and present an idea for a new classification based on this functional capacity.
The memBc ELISpot assay, combined with flow cytometry, was applied to patients with confirmed CVID in comparison with age-matched healthy control subjects.
Ex vivo frequency of IgG-, IgM-, and IgA-secreting plasmablasts was significantly diminished by 27.2-, 2.4-, and 23.3-fold, respectively, compared with that seen in healthy control subjects. Moreover, in vitro differentiation of memBcs into antibody-secreting cells was 6.1-, 2.6-, and 3.7-fold significantly reduced for IgG-, IgM-, and IgA-secreting cells, respectively. Proliferation of memBcs correlates inversely to immunoglobulin-secreting capacity, suggesting compensatory hyperproliferation. Furthermore, patients with no serum IgA can still have a detectable IgA ELISpot assay result in vitro. Most importantly, the large heterogeneity of memBc function in patients with CVID homogenously grouped by means of fluorescence-activated cell sorting allowed additional subclassification based on memBc/plasmablast function.
These data suggest almost normal memBc/immunoglobulin-secreting plasmablast functionality in some patients if sufficient stimulatory signals are delivered, which might open up opportunities for new therapeutic approaches.
普通变异性免疫缺陷（CVID）患者群体由一组具有不同病因的患者组成，这些患者存在低丙种球蛋白血症，易发生反复感染、自身免疫和恶性肿瘤。尽管记忆 B 细胞（memBcs）是体液防御的关键因素，并且这些患者的数量通常会减少，但它们的功能并未纳入任何现行分类。
我们建立并验证了一种 memBc 酶联免疫斑点（ELISpot）检测法，该方法可揭示 memBcs 发展为分泌抗体的细胞的能力，并提出了一种基于该功能能力的新分类方法。
将 memBc ELISpot 检测法与流式细胞术相结合，应用于确诊的 CVID 患者，并与年龄匹配的健康对照组进行比较。
与健康对照组相比，IgG、IgM 和 IgA 分泌浆母细胞的 ex vivo 频率分别降低了 27.2、2.4 和 23.3 倍。此外，memBcs 体外分化为分泌抗体的细胞的能力分别降低了 6.1、2.6 和 3.7 倍，用于 IgG、IgM 和 IgA 分泌细胞。memBcs 的增殖与免疫球蛋白分泌能力呈负相关，表明代偿性过度增殖。此外，没有血清 IgA 的患者在体外仍可检测到 IgA ELISpot 检测结果。最重要的是，CVID 患者的 memBc 功能具有很大的异质性，但通过荧光激活细胞分选进行分组时，基于 memBc/浆母细胞功能的亚分类具有均一性。
如果提供足够的刺激信号，一些患者的 memBc/免疫球蛋白分泌浆母细胞功能几乎正常，这可能为新的治疗方法提供机会。
