Prevalence of IgA deficiency in adult systemic lupus erythematosus and the study of the association with its clinical and autoantibody profiles.

INTRODUCTION: IgA deficiency (IgAD) is the most common primary immunodeficiency, which can cause frequent infections. The association of IgA deficiency with systemic lupus erythematosus (SLE) is very important because of the high morbidity and mortality rates of infections in patients with this disease.
OBJECTIVES: To study the prevalence of IgA deficiency in SLE patients from southern Brazil and to compare the clinical and autoantibody profiles of SLE patients with and without IgA deficiency. PATIENTS AND METHODS: One hundred and eighty-nine SLE patients were submitted to serum IgA measurement by nephelometry. Levels of IgA below 50mg/dL were considered to be IgAD. Demographic data, clinical profile (presence of arthritis, psychosis, seizures, stroke, serositis, hemolytic anemia, leucopenia, thrombocytopenia, and nephritis) and autoantibody profiles (ANA, anti-Ro, anti-La, anti-Sm, anti-DNA, anti-RNP, lupus anticoagulant, and anticardiolipin IgG and IgM) were obtained from reviewing medical records. As control, we used literature data from another study performed in the same geographical area. Data were analyzed through contingency and frequency tables, applying the Chi-square, Fisher, and Mann Whitney tests.
RESULTS: IgA deficiency was found in 11 (6.17%) patients (P < 0.001 in relation to controls). The association between IgA deficiency and clinical or autoantibody profile was not significant.
CONCLUSION: We concluded that a higher prevalence of IgA deficiency was observed in lupus patients than in controls. Deficiency of IgA did not have any particular laboratory or clinical effects on this population.