title: Mycobacterium bovis BCG decreases MHC-II expression in vivo on murine lung macrophages and dendritic cells during aerosol infection.
abstract: Mycobacterium tuberculosis and M. bovis BCG infect APCs. In vitro, mycobacteria inhibit IFN-gamma-induced MHC-II expression by macrophages, but the effects of mycobacteria on lung APCs in vivo remain unclear. To assess MHC-II expression on APCs infected in vivo, mice were aerosol-infected with GFP-expressing BCG. At 28 d, approximately 1% of lung APCs were GFP+ by flow cytometry and CFU data. Most GFP+ cells were CD11b(high)/CD11c(neg-mid) lung macrophages (58-68%) or CD11b(high)/CD11c(high) DCs (28-31%). Lung APC MHC-II expression was higher in infected mice than naïve mice. Within infected lungs, however, MHC-II expression was lower in GFP+ cells than GFP- cells for both macrophages and DCs. MHC-II expression was also inhibited on purified lung macrophages and DCs that were infected with BCG in vitro. Thus, lung APCs that harbor mycobacteria in vivo have decreased MHC-II expression relative to uninfected APCs from the same lung, possibly contributing to evasion of T cell responses.
authors.affiliation: Department of Pathology, Case Western Reserve University, Wolstein 6534, 10900 Euclid Avenue, Cleveland, OH 44106-7288, USA.
authors.forename: Nicole D
authors.initials: ND
authors.lastname: Pecora
authors.forename: Scott A
authors.initials: SA
authors.lastname: Fulton
authors.forename: Scott M
authors.initials: SM
authors.lastname: Reba
authors.forename: Michael G
authors.initials: MG
authors.lastname: Drage
authors.forename: Daimon P
authors.initials: DP
authors.lastname: Simmons
authors.forename: Nancy J
authors.initials: NJ
authors.lastname: Urankar-Nagy
authors.forename: W Henry
authors.initials: WH
authors.lastname: Boom
authors.forename: Clifford V
authors.initials: CV
authors.lastname: Harding