Complement and CpG, how do they interact?
Various components of the immune system work together to defend us against invading pathogens. The complement system is a key part of the innate immunity.
Recent studies indicated that complement activation and toll-like receptor (TLR)-9 stimulation interplay. Without complement activation, TLR-9 induced immune activation doesn’t take place. Considering that dendritic cells (DCs) are a source of complement proteins, I set out to evaluate if cytosine-guanosine nucleotide (CpG) 2006 can induce the synthesis of complement proteins in DCs. This has been shown to happen when using lipopolysaccharides (LPS) stimuli. Levels of complement products were analyzed by PCR and ELISA.
Results from my studies indicate that immature monocyte-derived DCs can enhance their production of complement proteins upon TLR-9 stimulation. As complement components mainly circulate with the blood in our body, DCs producing complement could potentially be a local source of complement factors at the site of CpG 2006 injection, thus affecting the immune response.
P
C3
C3b
C3b C3a
P
P C3a
C3b C3b B C3
D
Maturation Activation C5a
Upregulation of complement C3 mRNA expression and C3 protein secretion
C3 C3 C3
C3 C3
C3 C3 C3
C3 C3
secretion CpG2006
DC
CpG 2006 C3b C3a C5a FB FD Perperdin DCs
