BACKGROUND Rituximab (RTX) is efficient in steroid-dependent nephrotic syndrome (SDNS) in pediatric and adult patients. The aim of this study is to describe hypogammaglobulinemia as a side effect of RTX treatment. METHODS All pediatric patients (< 18 years old) of four French pediatric nephrology centers who received RTX for SDNS between 2010 and 2015 have been included. Clinical and biological data have been analyzed retrospectively before, during, and after RTX treatment. Hypogammaglobulinemia was defined as an IgG level < - 2 standard deviations for patient age. RESULTS A total of 107 pediatric patients have been included, 65.9% were boys, median age at nephrotic syndrome diagnosis was 3.1 interquartile range [IQ 2.24-5.45] years and age at RTX introduction was 11.7 [IQ 8.6-14.2] years. Twenty-one patients had hypogammaglobulinemia before the initiation of RTX. Of the patients, 25/86 had at least one hypogammaglobulinemia during B cell depletion or after B cell recovery while IgG levels at initiation were normal with a persisting hypogammaglobulinemia for 13 patients 1 year after B cell recovery. Patients who developed hypogammaglobulinemia were younger at RTX initiation with a median age of 8.2 years [IQ 6.3-12.4]. Among all the 46 patients with hypogammaglobulinemia during follow-up, 13 had a concomitant infection. CONCLUSIONS Hypogammaglobulinemia is a frequent complication of RTX treatment in younger children treated for SDNS. The use of RTX in children has to be carefully evaluated and their clinical and biological follow-up should be adapted to the age-dependent risk profile for hypogammaglobulinemia.

中文翻译：

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利妥昔单抗治疗的类固醇依赖型肾病综合征患者的免疫球蛋白血清水平。

背景技术利妥昔单抗（RTX）在小儿和成年患者的类固醇依赖型肾病综合征（SDNS）中有效。这项研究的目的是描述低球蛋白血症作为RTX治疗的副作用。方法包括2010年至2015年在法国四个儿科肾脏病中心接受RTX SDNS治疗的所有儿科患者（<18岁）。在RTX治疗之前，期间和之后对临床和生物学数据进行了回顾性分析。低球蛋白血症定义为患者年龄的IgG水平<-2标准差。结果共纳入107名儿科患者，其中65.9％为男孩，肾病综合征诊断的中位年龄为3.1四分位间距[IQ 2.24-5.45]岁，引入RTX的年龄为11.7 [IQ 8.6-14.2]岁。在开始RTX之前有21名患者患有低球蛋白血症。在这些患者中，有25/86在B细胞耗竭期间或B细胞恢复后至少有一次低球蛋白血症，而开始时IgG水平正常，而B细胞恢复1年后仍有13位患者持续存在低球蛋白血症。发生低血球蛋白血症的患者在RTX开始时较年轻，中位年龄为8.2岁[IQ 6.3-12.4]。在随访期间的所有46名低球蛋白血症患者中，有13名同时感染。结论低聚球蛋白血症是接受SDNS治疗的幼儿中RTX治疗的常见并发症。必须仔细评估儿童中使用RTX的情况，其临床和生物学随访应适应于年龄相关的低血球蛋白血症风险。