The Modulation of Adaptive Immune Responses by Bacterial Zwitterionic Polysaccharides

Figure 3

ZPSs modulate CD4 and CD8 T-cell responses. (a) Professional antigen presenting cells such as DCs internalize, process, and present ZPSs on MHCII molecules. The ZPS-MHCII complex is then recognized by TCRs of CD4 T cells in the presence of costimulatory molecules. This results in the activation and differentiation of CD4 T cells. ZPS-activated CD4 T cells produce different cytokines and have diverse immune function such as (1) inducing intraabdominal abscess, (2) helping to balance Th1/Th2 immune responses, (3) inducing the differentiation of proinflammatory IL-17 T cells, (4) inducing IL-10 producing anti-inflammatory CD4 T regs, and (5) differentiate into memory phenotype. (b) In contrast to the CD4 T-cell activation which requires recognition of ZPS-MHCII complex by TCR, ZPS activation of CD8 T cells do not require antigen processing and presentation. ZPS crosslinking of the TCRs activate CD8 T cells. ZPS-activated CD8 T cells differentiate into CD8+CD28^- Treg and have different immune modulatory effects such as inhibition of abscess induction and CD4 T-cell activation.