Research Center for Immunodeficiencies, Pediatrics Center of Excellence, Children's Medical Center, Tehran University of Medical Sciences, 62 Gharib Street, Tehran, Iran.
Int Arch Allergy Immunol. 2011;156(4):462-8. doi: 10.1159/000323903. Epub 2011 Aug 10.
Selective IgA deficiency (SIGAD) is the most common primary antibody deficiency, characterized by significant decreased serum levels of IgA in the presence of normal IgG and IgM. Despite several investigations into the nature of the disease, the exact pathophysiology of SIGAD is still unknown.
In this study, switched memory B cells (CD19+/CD27+/IgD- cell population) of 28 patients with SIGAD and 28 matched healthy controls were investigated using flow cytometry.
The percentage of switched memory B cells in all healthy controls was more than 0.4%. In SIGAD patients, who were classified as group I, the percentage of switched memory B cells was less than 0.4% (0.34 ± 0.06) in 7 patients (25%). The remaining 21 patients were designated as group II (1.74 ± 0.12%). The mean concentration of IgG in group I was significantly lower than in group II (1,014 ± 278 vs. 1,388 ± 406 mg/dl, p = 0.028). Comparison of clinical features between the 2 groups revealed that episodes of pneumonia during the course of disease were significantly higher in group I than in group II (p = 0.002). Autoimmune diseases in group I (57.1%) were also significantly higher (p = 0.01) than in group II (23.8%). The prevalence of bronchiectasis was 57% in group I, while only 1 patient (4.7%) in group II developed bronchiectasis (p = 0.006). Specific antibody deficiency in group I was documented in 5 patients and in group II in 4 patients (p = 0.01).
The classification of SIGAD patients by assessment of switched memory B cells could help physicians with the clinical prognosis for these patients, whereas the patients with reduced switched memory B cells are prone to severe phenotypes.
选择性 IgA 缺乏症（SIGAD）是最常见的原发性抗体缺乏症，其特征是血清 IgA 水平显著降低，而 IgG 和 IgM 水平正常。尽管对该疾病的性质进行了多项研究，但 SIGAD 的确切病理生理学仍不清楚。
本研究采用流式细胞术检测了 28 例 SIGAD 患者和 28 例匹配健康对照者的转换记忆 B 细胞（CD19+/CD27+/IgD-细胞群）。
所有健康对照者的转换记忆 B 细胞百分比均大于 0.4%。在 SIGAD 患者中，根据分类，第 I 组患者的转换记忆 B 细胞百分比小于 0.4%（7 例患者中为 0.34 ± 0.06），占 25%。其余 21 例患者被指定为第 II 组（1.74 ± 0.12%）。第 I 组患者的 IgG 平均浓度明显低于第 II 组（1,014 ± 278 与 1,388 ± 406 mg/dl，p = 0.028）。对两组的临床特征进行比较发现，第 I 组患者疾病过程中肺炎发作的频率明显高于第 II 组（p = 0.002）。第 I 组（57.1%）患者的自身免疫性疾病发生率也明显高于第 II 组（23.8%，p = 0.01）。第 I 组支气管扩张的患病率为 57%，而第 II 组仅有 1 例（4.7%）患者发生支气管扩张（p = 0.006）。第 I 组有 5 例患者存在特异性抗体缺乏，第 II 组有 4 例患者存在特异性抗体缺乏（p = 0.01）。
通过评估转换记忆 B 细胞对 SIGAD 患者进行分类有助于医生预测这些患者的临床预后，而转换记忆 B 细胞减少的患者更容易出现严重表型。
