Different Roles of Interleukin-23 During the Epicutaneous Sensitization and the Antigen Exposure to the Airways On Airway Inflammation and Responsiveness in Mice

S A T U R D A Y 155 CD49d+ Neutrophils Connect the Viral and Hygiene Hypotheses Sheila S. Bhat, Desire Hunter, Erika Buell, Dorothy S. Cheung, MD, FAAAAI, Mitchell H. Grayson, MD, FAAAAI; Medical College of Wisconsin, Medical College of Wisconsin, Milwaukee, WI. RATIONALE: Two hypotheses have been proposed to explain the increase in atopic disease. The viral and hygiene hypotheses are well known; however, it is not known if they could both play a role in the same individual. We utilized a well-characterized mouse model where paramyxoviral infection with Sendai virus (SeV) leads to atopic disease. The development of this post-viral atopic disease depends upon accumulation of CD49d+ neutrophils in the airway. Respiratory exposure to lipopolysaccharide (LPS), however, elicits a strong recruitment of CD49d– neutrophils to the airway. We hypothesized that exposure to LPS in SeV infected mice would reduce the frequency of CD49d+ neutrophils, thus preventing development of atopic disease. METHODS: C57BL6 mice were inoculated intranasally with SeV and given LPS (1, 3, and 10mg) at 0, 24, 48, and 60 hours later. Three days post SeV inoculation bronchoalveolar lavage (BAL) was performed. Flow cytometry was performed to determine the frequency of CD49d+ and CD49dneutrophils in the BAL. RESULTS: Administering 10 mg LPS at 60 hours post SeV infection was most effective in reducing CD49d+ neutrophils (17.661.7% versus 2.460.2%, 10 mg LPS versus no LPS, N54-5 p