Anti-Rat IgG2b polyclonal antibody

The cationic dimethyldioctadecylammonium/trehalose 6,6,9-dibehenate (DDA/TDB) liposome is as a strong adjuvant system for vaccines, with remarkable immunostimulatory activity. The mucosal administration of vaccines is a potential strategy for inducing earlier and stronger mucosal immune responses to infectious diseases. In this study, we assessed whether the intranasal administration of cationic DDA/TDB liposomes combined with influenza antigen A (H3N2) can be used as a highly efficacious vaccine to induce mucosal and systemic antibody responses. Confocal laser scanning microscopy and a flow-cytometric analysis showed that the uptake of the cationic DDA/TDB liposome carrier was significantly higher than that of neutral 1,2-distearoyl-sn-glycero-3-phosphocholine/cholesterol (DSPC/Chol) or cationic 1,2-dioleoyl-3-trimethylammonium-propane/3-(N-[N,N-dimethylaminoethane]-carbamoyl (DOTAP/DC-Chol) liposomes. Our results indicate that the cationic DDA/TDB liposome is more effective in facilitating its uptake by dendritic cells (DCs) in vitro than the DSPC/Chol or DOTAP/DC-Chol liposome. DCs treated with DDA/TDB liposomes strongly expressed CD80, CD86, and MHC II molecules, whereas those treated with DSPC/Chol or DOTAP/DC-Chol liposomes did not. C57BL/6 mice intranasally immunized with H3N2-encapsulating cationic DDA/TDB liposomes had significantly higher H3N2-specific s-IgA levels in their nasal wash fluid than those treated with other formulations. The DDA/TDB liposomes also simultaneously enhanced the serum IgG IgG2a, IgG1, and IgG2b antibody responses. In summary, DDA/TDB liposomes effectively facilitated their uptake by DCs and DCs maturation in vitro, and induced significantly higher mucosal IgA, systemic IgG, IgG1, and IgG2b antibody titres than other formulations after their intranasal administration in vivo. These results indicate that DDA/TDB liposomes are a promising antigen delivery carrier for clinical antiviral applications.

Goodpasture disease is an autoimmune kidney disease mediated by autoantibodies against noncollagenous domain 1 (NC1) monomers of alpha 3(IV) collagen that bind to the glomerular basement membrane (GBM), usually causing rapidly progressive glomerulonephritis (GN). We identified a novel type of human IgG4-restricted anti-GBM autoantibodies associated with mild nonprogressive GN, which specifically targeted alpha 345NC1 hexamers but not alpha 3NC1 monomers. The mechanisms eliciting these anti-GBM autoantibodies were investigated in mouse models recapitulating this phenotype. Wild-type and Fc gamma RIIB-/- mice immunized with autologous murine GBM NC1 hexamers produced mouse IgG1-restricted autoantibodies specific for alpha 345NC1 hexamers, which bound to the GBM in vivo but did not cause GN. In these mice, intact collagen IV from murine GBM was not immunogenic. However, in Col4a3(-/-) Alport mice, both intact collagen IV and NC1 hexamers from murine GBM elicited IgG Abs specific for alpha 345NC1 hexamers, which were not subclass restricted. As heterologous Ag in COL4A3-humanized mice, murine GBM NC1 hexamers elicited mouse IgG1, IgG2a, and IgG2b autoantibodies specific for alpha 345NC1 hexamers and induced anti-GBM Ab GN. These findings indicate that tolerance toward autologous intact alpha 345(IV) collagen is established in hosts expressing this Ag, even though autoreactive B cells specific for alpha 345NC1 hexamers are not purged from their repertoire. Proteolysis selectively breaches this tolerance by generating autoimmunogenic alpha 345NC1 hexamers. This provides a mechanism eliciting autoantibodies specific for alpha 345NC1 hexamers, which are restricted to noninflammatory IgG subclasses and are nonnephritogenic. In Alport syndrome, lack of tolerance toward alpha 345(IV) collagen promotes production of alloantibodies to alpha 345NC1 hexamers, including proinflammatory IgG subclasses that mediate posttransplant anti-GBM nephritis. The Journal of Immunology, 2013, 190: 1424-1432.