Background/Purpose: : Systemic lupus erythematosus (SLE) is characterized by B cell activation, elevated serum IgG and prominent circulating immune complexes. However, hypogammaglobulinemia in SLE patients is thought to be rare and it is unclear whether this is associated with SLE or is a transient effect of immunosuppressive treatment.  Approximately 1% of patients with common variable immunodeficiency (CVID) develop symptoms or laboratory abnormalities that support the diagnosis of SLE or will manifest an SLE-like syndrome. CVID can also rarely develop in patients with established SLE. We retrospectively reviewed our pediatric SLE cases at Washington University with the goal of identifying clinical and laboratory characteristics in patients with hypogammaglobulinemia.

Methods: 115 SLE cases seen in our Pediatric Rheumatology clinic from 1997-2011 were reviewed. Eighty six patients with inclusion criteria of having an IgG level within 3 months of diagnosis and more than one IgG level during follow-up were included in this study. Excluded were patients with insufficient data for SLEDAI scoring and presence of known immunodeficiency states.  Hypogammaglobulinemia was defined as an IgG level <500 mg/dl (2 SD below mean for age in pediatric population) on more than two occasions. Analysis of the different variables was done using SPSS version 10 for Windows.

Results: Seven percent (6/86) of pediatric SLE patients were found to have hypogammaglobulinemia with a median onset of 27 months (0-72 months) after SLE diagnosis. There was no significant difference in the mean age of patients with and without hypogammaglobulinemia (13.66 years and 14.41 years respectively). The risk of developing hypogammaglobulinemia was ~ 10x higher in males than female (p=0.009). There was no significant difference in the binned SLEDAI scores (≥10 and <10) between cohorts.  However, presence of lupus nephritis (p-value=0.004) and an IgG level of <1500 mg/dl at diagnosis (RR=4.88; 95% CI=1.00 – 24.97; p = 0.05) were both associated with hypogammaglobulinemia. Rituximab treatment did not significantly increase risk of developing hypogammaglobulinemia. Using multivariate analysis, male gender and an IgG level of less than 1500 mg/dl at diagnosis continued to show significant association with hypogammaglobulinemia in SLE.  Double stranded DNA antibody, complement and albumin levels did not correlate with hypogammaglobulinemia.  Interestingly, two patients with SLE and hypogammaglobulinemia had IgG levels less than 500 mg/dl within three months of diagnosis, suggesting that their hypogammaglobulinemia preceded or coincided with the onset of SLE.  Two other patients exhibited concomitantly low IgA levels without symptoms. Two patients had recurrent sinopulmonary infections with poor to no vaccine response and required replacement IVIG treatment.

 Conclusion: Immunoglobulin deficiency can co-exist with pediatric SLE independent of biologic drug treatment. Measurement of immunoglobulin levels in SLE could help identify patients at greater risk for infection that require more aggressive follow-up to reduce morbidity.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/hypogammaglobulinemia-in-pediatric-systemic-lupus-erythematosus/