Effect of Ranitidine on Hyper-IgE Recurrent Infection (Job's) Syndrome

Hyper-immunoglobulin E (IgE) syndrome (HIES) is a rare primary immunodeficiency characterized by eczema, recurrent skin and lung infections, elevated serum IgE, and multiple connective tissue and skeletal abnormalities. The autosomal dominant form of HIES is caused primarily by a mutation in the STAT3 gene. Patients with HIES produce IgE antibodies specific for Candida albicans and Staphylococcus aureus, two of the common pathogens in this population. We hypothesize that the presence of pathogen-specific IgE, combined with continuous exposure to these ubiquitous agents, leads to chronic IgE-mediated histamine release from basophils and mast cells, with subsequent pathogen-specific immune tolerance and an increase in pathogen-specific T regulatory cells. We plan to test this hypothesis through clinical and immunologic evaluation of HIES patients before, during, and after histamine-2 receptor (H2) blocker therapy with ranitidine through a prospective, placebo-controlled crossover study. We chose this therapy because histamine has been shown to stimulate interleukin-10 (IL-10), a major down regulatory cytokine, through the H2 receptor, and clinical improvement has been observed in several patients treated with H2 blockers. Laboratory studies will include determinations of pathogen-specific immunoglobulin G4 (IgG4):IgE ratios, basophil activation, IL-10 producing regulatory T-cells, cellular proliferative responses to staphylococcal and candidal antigens, and functional testing of regulatory T-cells. Clinical evaluations will include comprehensive history and physical examination, dermatologic evaluation, genetic evaluation for clinical severity scoring of HIES, pulmonary function tests, and chest computerized tomography (CT) examination. Through this study, we will further our understanding of the immunologic abnormalities of HIES and determine whether a larger prospective, double-blind trial of H2 blockade as adjunctive therapy for HIES is indicated.