B cell (inactive)
- B cells are lymphocytes
- they play a large role in the immune response
- the functions of B cells are:
- to make antibodies against antigens
- perform the role of antigen-presenting cells (APCs)
- and develop into memory B cells after activation by antigen interaction
- they kill pathogens
- B cells are an essential component of the adaptive immune system
- B cells circulate in the blood and lymphatic system
B and T memory cell
- formed from activated B and T cells that are specific to the antigen encountered during the primary immune response.
- These cells are able to live for a long time, and can respond quickly following a second exposure to the same antigen.
- if a person has an infection, his/her memory cells remember how to get rid of the virus that causes the disease
- once the virus has been fought off once any future infections will unlikley result in a person becoming ill.
B effector cell and plasma cells
- B effector cells are made when the B cell is stimulated
- the B cell differentiates into B effector cells
- The B effector cells can the differentiate into plasma cells.
- these plasma cells then secrete antibodies.
- these antibodies then bind to antigens identifying them for easier destruction.
T helper cell and active T killer cell
T helper cells:
When activated these stimulate the B cells
- the B cells then divide and become capable of producing antibodies
- they also enhances the activity of pathogens
active T killer cells:
- these destroy cells with antigens on their surface that are recognised as non self
- this includes body cells infected with pathogens
- unfortunately it also includes tissues recieved as a transplant from another person.
Macrophages and neutrophils
- macrophages and neutrophils are a type of phagocyte
- phagocytes are white blood cells that engulf bacteria and other foreign matter in the blood and tissues.
- a bacterium with antigens on its surface is engulfed by a macrophage
- is is then enclosed in a vacuole
- lysosomes fuse with the vacuole releasing enzymes that destroy the foreign material.
- neutrophils leave blood capillaries by squeezing between the cells of capillary walls
- they ingest and destory bacteria
Natural killer cell
- natural killer cells are a type of lymphocyte
- they are found in the blood and lymph
- unlike B and T cells they do not use specific antigen recognition
- instead they provide immunity against cells invaded by viruses and cancerous cells