The T Lymphocyte Response
- Lymphocytes are another type of white blood cell
- They play an important part in the specific immune response
- They are smaller than phagocytes
- They have a large nucleus that fills most of the cell
- They are produced in the bone marrow before birth
- There are two types of lymphocytes (with different modes of action). The two types of lymphocytes are:
- T-lymphocytes (T cells)
- B-lymphocytes (B cells)
T-lymphocytes and the cellular immune response
- Immature T-lymphocytes leave the bone marrow to mature in the thymus
- Mature T-lymphocytes have specific cell surface receptors called T cell receptors
- These receptors have a similar structure to antibodies and are each specific to one antigen
The maturation of T-lymphocytes – some become helper T cells and others become killer T cells
- T-lymphocytes are activated when they encounter (and bind to) their specific antigen that is being presented by one of the host’s cells (host cells being the human’s own cells)
- This antigen-presenting host cell might be a macrophage or a body cell that has been invaded by a pathogen and is displaying the antigen on its cell surface membrane
- These activated T-lymphocytes (those that have receptors specific to the antigen) divide by mitosis to increase in number (similar to the clonal selection and clonal expansion of B-lymphocytes)
- These T-lymphocytes differentiate into two main types of T cell:
- helper T cells
- cytotoxic T cells(also known as killer T cells)
