Immunoglobulin E deficiency: A forgotten clue pointing to possible immunodeficiency?

Abstract

Background: Patients with primary antibody deficiency often have delayed diagnosis. Very low IgE, found during investigations for allergy, may be a marker for other immunodeficiency. Methods: We introduced a new laboratory policy of testing cases with very low IgE levels for possible linked antibody deficiency. The data represent an audit of routine results collected over two years. Results: Very low IgE (≤2 IU/mL) was identified in 85/2622 (3.2%) routine patient samples. Two children and four adult patients were found to have one or more classes of immunoglobulin below the reference range for age. In 2/6, the initiative of the laboratory led to a new unsuspected diagnosis of antibody immunodeficiency. Conclusions: Common variable immunodeficiency continues to be overlooked as a primary cause of lung disease in adults. Very low serum IgE should trigger appropriate investigation (immunoglobulin quantification and serum electrophoresis).