An Affinity Based Complex Artificial Immune System

2. Immune Response Mechanism

Figure 1.

Immune response process

Figure 1 depicts the immune response process in detail considering the affinity interactions. When an antigen invades the host, antigen present cells first internalize the invaded antigen to secrete antigenic peptides, either by phagocytosis or by endocytosis. These antigenic peptides join to major histocompatibility complex (MHC) and display on the surface of antigen presenting cell together. Th cells recognize the peptide-MHC molecules through T-cell receptors. Activated Th cells divide and secrete interleukin (IL+), or other chemical signals, which mobilize other components (B cells etc.) of the immune system. It is remarked that Th cells with different receptors recognize complex of peptide-MHC with different affinity. If Th cell receptors and antigens are not quite complementary, they may still bind, but with a low affinity. However, B cells can also be activated by antigens directly. Activated B cells can divide and differentiate into plasma cells and memory cells. Plasma cells secrete the antibodies to destroy the invaded antigen. When antigen is destroyed, Ts cells are activated and secrete suppressing signal interleukin (IL-) to Th cells to terminate immune response. As for the memory B cells, when they encounter the same antigens once again, they will divide into plasma cells rapidly, and generate abundant antibodies soon, which is called the second response.