C-reactive protein enhances immunity to Streptococcus pneumoniae by targeting uptake to Fc gamma R on dendritic cells.

C-Reactive Protein Enhances Immunity to Streptococcus pneumoniae by Targeting Uptake to Fc R on Dendritic Cells

Protection from Streptococcus pneumoniae infection by C-reactive protein and natural antibody requires complement but not Fc gamma receptors.

Streptococcus pneumoniae is an important human pathogen and the most common cause of community-acquired pneumonia. Both adaptive and innate immune mechanisms provide protection from infection. Innate immunity to S. pneumoniae in mice is mediated by naturally occurring anti-phosphocholine (PC) Abs and complement. The human acute-phase reactant C-reactive protein (CRP) also protects mice from let...

C-reactive protein increases cytokine responses to Streptococcus pneumoniae through interactions with Fc gamma receptors.

Streptococcus pneumoniae is the most common organism responsible for community acquired pneumonia and meningitis. In pneumococcal pneumonia, a strong local inflammatory cytokine response reduces the frequency of bacteremia and increases survival. The initiation of this cytokine response by innate recognition of bacterial cell wall components through TLR has been described, but the role of solub...

Immune complex-mediated antigen presentation induces tumor immunity.

Antigen uptake receptors on dendritic cells (DCs) provide efficient entry for the initiation of antigen-specific adaptive immunity. Here we show that targeting of antigen to Fc receptors on DCs accomplishes combined activation of Th1 CD4 and CD8 effector responses in vivo, namely delayed-type hypersensitivity and tumor immunity. Tumor immunity specific for ovalbumin-expressing tumors was provid...

Dendritic cell-derived exosomes express a Streptococcus pneumoniae capsular polysaccharide type 14 cross-reactive antigen that induces protective immunoglobulin responses against pneumococcal infection in mice.

Exosomes activate T cells in vivo, but whether exosomes are able to induce humoral immune responses is still unknown. We found that dendritic cells, but not other immune cells, constitutively release an exosome-associated glycoconjugate that is cross-reactive with the capsular polysaccharide of Streptococcus pneumoniae type 14 (Cps14-CRA). Cps14-CRA was localized to the cholesterol-enriched mic...