title: Role of IgA in the defense against respiratory infections IgA deficient mice exhibited increased susceptibility to intranasal infection with Mycobacterium bovis BCG.
abstract: IgA is the predominant Ig isotype in mucosal tissue and is believed to be involved in defense against viral and bacterial infections at these sites. Here, we examined the role of IgA in the protection against intranasal (i.n.) infection with Mycobacterium bovis Bacillus Calmette-Guerin (BCG). IgA deficient (IgA-/-) mice and wild type non-targeted littermate (IgA+/+) mice were immunized by i.n. route with the mycobacterium surface antigen PstS-1 formulated with cholera toxin (CT). Our data showed that IgA-/- mice were more susceptible to BCG infection compared to IgA+/+ mice, as revealed by the higher bacterial loads in the lungs and bronchoalveolar lavage (BAL). Analysis of the Ig levels and the antibody responses to PstS-1 showed that IgA-/- mice had no detectable IgA either in the saliva or in the BAL. However, these mice displayed higher levels of total and specific IgM than IgA+/+ mice in both mucosal fluids. More importantly, analysis of the cytokine responses revealed a reduction in the IFN-gamma and TNF-alpha production in the lungs of IgA-/- compared to IgA+/+ mice. Altogether, our results suggest that IgA may play a role in protection against mycobacterial infections in the respiratory tract by blocking the pathogen entrance and/or by modulating the pro-inflammatory responses.
authors.affiliation: Department of Immunology, Stockholm University, Stockholm, Sweden. ariane@imun.su.se
authors.forename: Ariane
authors.initials: A
authors.lastname: Rodríguez
authors.forename: Anna
authors.initials: A
authors.lastname: Tjärnlund
authors.forename: Juraj
authors.initials: J
authors.lastname: Ivanji
authors.forename: Mahavir
authors.initials: M
authors.lastname: Singh
authors.forename: Irene
authors.initials: I
authors.lastname: García
authors.forename: Ann
authors.initials: A
authors.lastname: Williams
authors.forename: Philip D
authors.initials: PD
authors.lastname: Marsh
authors.forename: Marita
authors.initials: M
authors.lastname: Troye-Blomberg
authors.forename: Carmen
authors.initials: C
authors.lastname: Fernández
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000276:immunology; D000281:Administration, Intranasal; D000818:Animals; D001426:Bacterial Proteins / Q000276:immunology; D002417:Cattle; D015169:Colony Count, Microbial; D016207:Cytokines / Q000096:biosynthesis; D004797:Enzyme-Linked Immunosorbent Assay; D017098:IgA Deficiency / Q000276:immunology*; D007070:Immunoglobulin A / Q000276:immunology*; D008168:Lung / Q000382:microbiology; D051379:Mice; D018345:Mice, Knockout; D009163:Mycobacterium bovis; D012141:Respiratory Tract Infections / Q000276:immunology*; D014380:Tuberculosis, Bovine / Q000276:immunology* / Q000382:microbiology
chemical_list: D018528:ATP-Binding Cassette Transporters; D001426:Bacterial Proteins; D016207:Cytokines; D007070:Immunoglobulin A; C102010:PstS-3 protein, Mycobacterium tuberculosis