WJEC Biology for A2: Student Bk

St u dy point T and B lymphocytes generate the cell-mediated response; B lymphocytes generate the humoral response. ■ B and T lymphocytes to undergo clonal expansion , i.e. to divide repeatedly into genetically identical cells, forming a large population of cells specific to a particular antigen. These cells differentiate into the various classes of lymphocyte. ■ B lymphocytes to make antibodies. Microbes agglutinated by antibodies are engulfed by phagocytic cells Fighting infection The primary immune response ▪ On the first exposure to an antigen, there is a short latent period in which macrophages engulf the foreign antigen or the cell or virus to which it is attached, and incorporate the antigenic molecules into their own cell membranes. This is called antigen presentation and macrophages are therefore a type of antigen-presenting cell. ▪ T helper cells detect these antigens and respond by secreting cytokines. ▪ The B plasma cells secrete antibodies for about 3 weeks. The symptoms of infection subside. Summary of the primary response stem cells in bone marrow T memory T killer T helper cytokines B plasma cells antibodies agglutinate microbes antigens presented on cell membrane B memory T lymphocytes B lymphocytes macrophages engulf microbes Option A: Immunology and disease 273