Fig. 2

The immune system response to vaccination. The vaccine is injected intramuscularly, and subsequently the protein antigen is taken up by dendritic cells activated by pattern recognition receptors (PRRs) to danger signals in the adjuvant. Here, MHC molecules on the surface of dendritic cells can present peptides of the vaccine protein antigen, which in turn leads to activation of T cells via their T-cell receptor (TCR). Following this, B cells can be developed in the lymph node by T cells. This development is a result of the combination of soluble antigen with the B-cell receptor (BCR). The production of plasma cells produces a rapid rise in serum antibody levels over the next 2 weeks. Memory B cells are also generated, thus mediating immune memory. Of note, CD8⁺ memory T cells proliferate rapidly when they confront a pathogen, and CD8⁺ effector T cells also have a pivotal role to play in the obliteration of infected cells