When a pathogen invades the body, it is first encountered by antigen-presenting cells (APCs) such as dendritic cells. These APCs process the pathogen and present its antigens on their surface. This presentation activates helper T cells, which then stimulate B cells to produce antibodies and cytotoxic T cells to kill infected cells. The adaptive immune system also has a memory component, allowing it to respond more rapidly and effectively upon subsequent exposures to the same pathogen.
