Relationship between autoimmune diseases and serum basal immunoglobulin E levels in patients with common variable immunodeficiency.

Autoimmune diseases can occur at any time in patients with common variable immunodeficiency (CVID). However, the relationship between low immunoglobulin E (IgE) levels and autoimmune diseases in patients with CVID remains poorly understood. We aimed to determine the relationship between autoimmunity and low IgE in patients with CVID. This retrospective cohort study was conducted by using data that had been collected from 62 adult patients with CVID between April 2012 and December 2021. Serum basal IgE levels were compared between patients with and patients without autoimmune disease. Overall, 23 of the 62 patients with CVID (37.1%) had at least one autoimmune disease (CVID-O). Autoimmune cytopenias, mainly immune thrombocytopenic purpura, were observed in half of all the patients. Other autoimmune diseases present among the patients included rheumatological diseases, inflammatory bowel diseases, lymphoma, granulomatous lymphocytic interstitial lung disease, autoimmune hepatitis, alopecia, and multiple sclerosis. Serum IgE levels were measured at the time of diagnosis; IgE was undetectable (<2.5 IU/mL) in 82.6% of the patients with CVID-O (n = 19). The median (interquartile range) serum IgE value in the patients with CVID-O was 2 IU/mL (1-16 IU/mL), which was significantly lower than the median serum IgE value in patients with CVID and without autoimmune disease (p < 0.001). Low IgE levels in patients with CVID-O were an independent risk factor for the development of autoimmune disease in patients with CVID (odds ratio 3.081 [95% confidence interval, 1.222-7.771]; p = 0.017). Low serum IgE levels were associated with the development of autoimmune disease in patients with CVID. The monitoring of serum IgE levels in patients with CVID may be useful in the early diagnosis and treatment of autoimmune diseases.