This issue of Immunology and Allergy Clinics of North America, guest edited by Dr. Rohit Katial, is devoted to Severe Asthma. Articles in this issue include: Epidemiology and Pulmonary Physiology of Severe Asthma; Linkage and Genetic Associations in Severe Asthma; Asthma COPD Overlap Syndrome (ACOS); Biomarkers in Severe Asthma; Imaging in Severe Asthma; Eosinophilic Phenotype; Neutrophilic and Pauci-immune Phenotypes; Role of Sleep Apnea and Gastroesophageal Reflux Disease in Severe Asthma; Role of Small Airways in Severe Asthma; Chronic Infection and Severe Asthma; Chronic Rhinosinusitis and Aspirin Associated Respiratory Disease; Psychosocial Factors in Severe Asthma; Traditional Therapies for Severe Asthma; and Emerging Biologics for Severe Asthma.

This issue of Immunology and Allergy Clinics provides a comprehensive review of the current state of biomarkers and their role in the asthma diagnostic and therapeutic algorithm.Since the last issue on Biomarkers, which published in 2007, significant research directly targeted at biomarker development and clinical trials with new biologics, using biomarkers such as exhaled nitric oxide, sputum and tissue eosinophilia as endpoints, has occurred.

This issue of Immunology and Allergy Clinics, guest edited by Drs. Flavia Hoyte and Rohit Katial, is devoted to Biomarkers in Allergy and Asthma. Articles in this issue include: Exhaled Nitric Oxide; Biomarkers in Exhaled Breath Condensate (EBC); Role of Eosinophils in Asthma; Bronchoprovocation Testing in Asthma; Periostin and DPP4; Role of Neutrophils in Asthma; Urinary LTE4; Biomarkers in Nasal Polyps; IgE as a Biomarker in Asthma; Genetics of Asthma; and Biomarker-directed Therapies for Asthma.