• Kathryn J Quigley, Catherine J Reynolds, Amelie Goudet, Eleanor J Raynsford, Ruhena Sergeant, Andrew Quigley, Stefan Worgall, Diana Bilton, Robert Wilson, Michael R Loebinger, Bernard Maillere, Daniel M Altmann, and Rosemary J Boyton.
• 1 Lung Immunology Group, Infectious Diseases and Immunity, Department of Medicine, Medical Research Council and Asthma United Kingdom Centre in Allergic Mechanisms of Asthma, Centre for Respiratory Infection, Hammersmith Hospital, Imperial College, London, United Kingdom.
• Am. J. Respir. Crit. Care Med. 2015 Jun 1; 191 (11): 125012641250-64.

RationalePseudomonas aeruginosa (PA) is an environmental pathogen that commonly infects individuals with cystic fibrosis (CF) and non-CF bronchiectasis, impacting morbidity and mortality. To understand the pathobiology of interactions between the bacterium and host adaptive immunity and to inform rational vaccine design, it is important to understand the adaptive immune correlates of disease.ObjectivesTo characterize T-cell immunity to the PA antigen outer membrane porin F (OprF) by analyzing immunodominant epitopes in relation to infection status.MethodsPatients with non-CF bronchiectasis were stratified by frequency of PA isolation. T-cell IFN-γ immunity to OprF and its immunodominant epitopes was characterized. Patterns of human leukocyte antigen (HLA) restriction of immunodominant epitopes were defined using HLA class II transgenic mice. Immunity was characterized with respect to cytokine and chemokine secretion, antibody response, and T-cell activation transcripts.Measurements And Main ResultsPatients were stratified according to whether PA was never, sometimes (<50%), or frequently (≥50%) isolated from sputum. Patients with frequent PA sputum-positive isolates were more likely to be infected by mucoid PA, and they showed a narrow T-cell epitope response and a relative reduction in Th1 polarizing transcription factors but enhanced immunity with respect to antibody production, innate cytokines, and chemokines.ConclusionsWe have defined the immunodominant, HLA-restricted T-cell epitopes of OprF. Our observation that chronic infection is associated with a response of narrowed specificity, despite strong innate and antibody immunity, may help to explain susceptibility in these individuals and pave the way for better vaccine design to achieve protective immunity.

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