Immune Response in H. pylori-Associated Gastritis and Gastric Cancer

Figure 2

CTLA-4 inhibits T cell activation and function via CD80/CD86. In normal, CD28 combines with CD80/CD86 and delivers subsequent phosphorylation signals to maintain T cell survival. Binding of CTLA-4 to CD80/CD86 inhibits T cell activation via two various pathways. The one is CTLA-4 competition with CD28 which will block phosphorylation processes by PP2A, to disturb the normal T cell activation. Another one is that T cell motility can also be promoted and thus leads to a relative decrease in the contact time between T cells and APC and T cell activation. In addition, this signal causes some changes in APC and induces IDO. IDO has an effect on inhibiting immunity and facilitating metaplasia. Abbreviations: CD80/CD86: B7 family; CTLA-4: cytolytic T lymphocyte-associated antigen 4; LCK: lymphocyte-specific protein tyrosine kinase; ITAMs: immunotyrosine activation motifs; PP2A: protein phosphatase 2A; ZAP70: zeta-chain-associated protein of 70 kDa; IDO: indoleamine 2,3-dioxygenase.