Raif S. Geha, MD, is the James L. Gamble Professor of Pediatrics at the Harvard Medical School and chief of the Division of Immunology, Allergy, and Rheumatology at Boston Children's Hospital. He combines clinical practice with research on immunodeficiency in patient and transgenic mice, and investigation of the pathogenesis of atopic dermatitis.

Luigi D. Notarangelo, MD, is chief of the Laboratory of Clinical Immunology and Microbiology at the National Institute of Allergy and Infectious Diseases, National Institute of Health. He is a leader in the study of the molecular and cellular mechanisms of human primary immune deficiencies and in the treatment of these disorders. He has served as president of the European Society for Immunology and of the Clinical Immunology Society.