Hypogammaglobulinemia in pediatric systemic lupus erythematosus

Objective: Systemic lupus erythematosus (SLE) is a systemic autoimmune disease typically associated with elevated serum immunoglobulin G (IgG). Hypogammaglobulinemia in SLE patients has been attributed to immunosuppressive treatment or a transient effect associated with nephrotic syndrome. We retrospectively reviewed pediatric SLE patients from a single institution to identify patients with hypogammaglobulinemia and risk factors for hypogammaglobulinemia. Methods: A total of 116 pediatric SLE cases from 1997 to 2011 were reviewed and patients with hypogammaglobulinemia (IgG500 mg/dl) were identified. The two cohorts were evaluated for association with age, sex, presence of lupus nephritis at SLE diagnosis, disease activity at diagnosis, initial IgG level, and drug treatment. Results: Eighty-six patients were included in our study, with a median age of 15 years and a median follow-up of 39.5 months. Seven percent (six of 86) of patients had hypogammaglobulinemia with a median onset of 27 months (0-72 months) after SLE diagnosis. Significant associations were noted for white race (p value 0.029), male sex (p value 0.009), and the presence of lupus nephritis at SLE diagnosis (p value 0.004). Use of immunosuppressive treatment did not show a statistical association with hypogammaglobulinemia, although two of the patients with hypogammaglobulinemia did receive rituximab. Most patients with hypogammaglobulinemia received intravenous immunoglobulin (IVIG) replacement therapy because of infections and/ or concern for infection. Conclusion: Measurement of immunoglobulin levels during treatment in SLE could help identify patients with hypogammaglobulinemia who might require more aggressive follow-up to monitor for increased risk of infection and need for IVIG treatment. A prospective study is needed to validate associated risk factors identified in this study.