title: B cell antigen presentation promotes Th2 responses and immunopathology during chronic allergic lung disease.
abstract: BACKGROUND
  The role of B cells in allergic asthma remains undefined. One mechanism by which B cells clearly contribute to allergic disease is via the production of specific immunoglobulin, and especially IgE. Cognate interactions with specific T cells result in T cell help for B cells, resulting in differentiation and immunoglobulin secretion. Proximal to (and required for) T cell-dependent immunoglobulin production, however, is antigen presentation by B cells. While interaction with T cells clearly has implications for B cell function and differentiation, this study investigated the role that B cells have in shaping the T cell response during chronic allergic lung disease.
  
  
  RESULTS
  In these studies, we used a clinically relevant mouse model of chronic allergic lung disease to study the role of B cells and B cell antigen presentation in this disease. In these studies we present several novel findings: 1) Lung B cells from chronically allergen challenged mice up-regulated MHC II and costimulatory molecules CD40, CD80 and CD86. 2) Using in vitro studies, B cells from the lungs of allergen challenged mice could present antigen to T cells, as assessed by T cell proliferation and the preferential production of Th2 cytokines. 3) Following chronic allergen challenge, the levels of Th2 cytokines IL-4 and IL-5 in the lungs and airways were significantly attenuated in B cell -/- mice, relative to controls. 4) B cell driven Th2 responses and mucus hyper secretion in the lungs were dependent upon MHC II expression by B cells.
  
  
  CONCLUSIONS
  Collectively, these results provide evidence for antigen presentation as a novel mechanism by which B cells contribute to chronic allergic disease. These findings give new insight into the mechanisms by which B cells promote asthma and other chronic diseases.
authors.affiliation: Department of Pathology, University of Michigan, Ann Arbor, Michigan, United States of America. denmklin@umich.edu
authors.forename: Dennis M
authors.initials: DM
authors.lastname: Lindell
authors.forename: Aaron A
authors.initials: AA
authors.lastname: Berlin
authors.forename: Matthew A
authors.initials: MA
authors.lastname: Schaller
authors.forename: Nicholas W
authors.initials: NW
authors.lastname: Lukacs