Antibody Structure and Function What are lymphocytes Lymphocytes
Antibody Structure and Function
What are lymphocytes? Lymphocytes are a type of white blood cell (leukocyte) found in the blood and lymph nodes. Lymphocytes recognise antigen molecules on the surface of pathogens, and co-ordinate the immune response against that pathogen. Collectively, lymphocytes can recognize millions of different antigens, due to the large variation of lymphocytes produced. 2 of 38 © Boardworks Ltd 2008
Humoral and Cellular Immune Responses - Involve lymphocytes B-lymphocytes – mature in bone marrow T-lymphocytes – mature in thymus B-lymphocytes produce antibodies – humoral response - T-lymphocytes directly affect cells – cellular response
Cellular immune response 4 of 38 © Boardworks Ltd 2008
Different types of lymphocytes 5 of 38 © Boardworks Ltd 2008
T-cells Phagocyte takes up pathogen. Antigens presented on surface of phagocyte (antigen-presenting cell). T-cell binds to antigen on APC. T-cell divides by mitosis and differentiates. Several types of T-cell produced, including memory cells, T-helper cells and cytotoxic Tcells.
T-cells
Humoral immune response 8 of 38 © Boardworks Ltd 2008
B-cells B-cell binds to antigen. B-cell to divides by mitosis and differentiates (may be stimulated by T-helper cell). Some cells formed are plasma cells – secrete antibodies. Some cells formed are memory cells – remain in blood for a period of time, providing immunity.
Clonal Selection There are thousands of B-cells present in the body, each with different receptors on its surface. When a cell is stimulated, it divides by mitosis (CLONING) and the plasma cells formed produce antibodies with the same shape as the receptors it had.
Artificial immunity 12 of 38 © Boardworks Ltd 2008
Immunological memory 13 of 38 © Boardworks Ltd 2008
Vaccines, lymphocytes and the secondary response Primary Response Secondary Response The first time a new antigen is The second time the antigen encountered, it takes time for is encountered, there already a number of memory B- and T-cells to respond. cells present. Antibodies are produced fairly The immune response is slowly as plasma cells are produced by mitosis of B-cells. quicker. Memory cells (B and T) remain in the blood for a period of time after the initial infection. 14 of 38 More antibodies are produced more quickly than in the primary response. © Boardworks Ltd 2008
- Slides: 13