Immunity, Vaccines, T-cells & B-cells
Immunity, Vaccines, T-cells & B-cells - How the body responds to invasion by foreign substances.
- Phagocytosis is literally cell-eating. Neutrophils, a type of white blood cell carry out phagocytosis. They surround the pathogen e.g. a bacterium and ingest the contents thus destroying it.
- T-cells and B-cells are really T-lymphocytes and B-lymphocytes. These cells are found in the lymphatic system which is allied to the blood system. They respond to antigens.
T-cells = whole cell attacks invading pathogen
T lymphocytes have the job of carrying receptors on their surface (T-receptors) to a foreign substance. The receptors have antigen-binding properties. They will lock on to an antigen on a foreign substance and carry out what is termed Cell-mediated immunity.
- The 3 main T-cell types have dramatic names: Cytotoxic T cells (actually seek out and destroy with foreign antigens), Helper T-cells (these help the other two) & Suppressor T-cells (these inhibit the immune response – they could be part of a homeostatic response to immune responses).
- All are lymph cells though, formed in the bone marrow like other blood cells. B-cells = mature B-cells secrete antibodies to the blood & lymph systems
B-lymphocytes have the job of carrying out immunity work once they have been modified into plasma cells. They carry out what is termed Antibody-mediated immunity.
These cells do not actually bind themselves to a foreign particle or body like the T-cells. B-cells, once converted into plasma cells, produce and secrete antibodies. The blood and lymph fluids transport the antibodies made by B-cells to the infected tissue.
The B-cells attack virus particles that have an antigen that can be locked on to.
Interesting Fact
Some B-cells do not change into plasma cells; they become Memory Cells and these produce small amounts of antibody long after an infection has been destroyed.
Helper T-cells will work with both T-cells and B-cells in attacking a viral particle Cytotoxic T-cells reach the cell in which a virus exists or is attacking, and destroy the cell
