title: Elevated production of Legionella-specific immunoglobulin A in A/J mice is accompanied by T-helper 1-type polarization.
abstract: Legionella pneumophila (Lpn) is a Gram-negative bacterium and an intracellular parasite that causes Legionnaires' disease. Secretion of immunoglobulin A (IgA) against Lpn on the mucosal surface of the upper respiratory tract may be important as a self-defense mechanism. A/J mice have been demonstrated to be permissive as to Lpn replication in macrophages due to a natural mutation in neuronal apoptosis inhibitory protein 5. We compared A/J and BALB/c mice as to IgA production after repeated intranasal immunization using a heat-killed Lpn in the presence of cholera toxin as a mucosal adjuvant. A/J mice secreted more Lpn-specific IgA in nasal washes than BALB/c mice. The Lpn-specific serum IgA level was also higher in A/J than BALB/c mice. Because both BALB/c and A/J mice are known to exhibit T-helper 2 (Th2)-biased immune responses, we examined whether the Lpn-specific IgA production is related to the stronger Th2 bias. There was no difference in IgG1 (Th2-controlled) while A/J mice produced more IgG2a (Th1-controlled), suggesting that the elevated IgA response was rather correlated with Th1-controlled isotype switching. Our results also suggest that A/J mice will be useful hosts for Lpn-specific IgA production such as for the preparation of IgA monoclonal antibodies.
authors.affiliation: Laboratory of Microbiology and Immunology and Global COE Program, University of Shizuoka School of Pharmaceutical Sciences, Shizuoka 422-8526, Japan.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Taniguchi
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Harada
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Hayashi
authors.forename: Takashi
authors.initials: T
authors.lastname: Tanikawa
authors.forename: Kohta
authors.initials: K
authors.lastname: Kurohane
authors.forename: Masaki
authors.initials: M
authors.lastname: Miyake
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Imai
mesh_terms: D000281:Administration, Intranasal; D000818:Animals; D002772:Cholera Toxin; D000939:Epitopes; D005260:Female; D018928:Immunity, Mucosal; D007117:Immunization, Secondary; D007070:Immunoglobulin A / Q000097:blood* / Q000235:genetics; D017578:Immunoglobulin Class Switching; D016952:Legionella pneumophila / Q000276:immunology* / Q000472:pathogenicity; D007877:Legionnaires' Disease / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D013045:Species Specificity; D018417:Th1 Cells / Q000276:immunology*; D018418:Th2 Cells / Q000276:immunology*; D014774:Virulence
chemical_list: D000939:Epitopes; D007070:Immunoglobulin A; D002772:Cholera Toxin