B-Lymphocytes and T-Lymphocytes

Lymphocytes are a type of white blood cell. They play an important role in the immune response.
All lymphocytes are made in the bone marrow.
Depending on where they mature, lymphocytes are divided into 2 main groups;
- B-cells.
- T-cells.

B Cells

B-cells are the lymphocytes responsible for producing antibodies.
Humans are born with millions of different B-cells.
B-cells mature in the bone marrow.
Once mature, they move to the lymph nodes**.**
Each B-cell produces a specific antibody with a unique shape, which is displayed on its surface.
When a B-cell's antibody matches an antigen, the B-cell multiplies (clones) and produces large quantities of the specific antibody.
After the infection is overcome, most B-cells die, but a small number remain as memory B-cells.
These provide long-term immunity by responding quickly to future infections by the same pathogen.

T-cells mature and are activated in the thymus gland (T for thymus).
T-cells do not produce antibodies.
There are four types of T-cells:

Helper T-cells multiply and release chemicals to stimulate (help) B-cells to multiply.
These B-cells then produce the correct antibodies.
Helper T-cells also stimulate the production of killer T-cells.

Killer T-cells attack and destroy abnormal body cells, including infected and cancerous cells.
Also known as natural killer (NK) cells because they are cytotoxic (cell-killing).

Suppressor T-cells inhibit the activity of B-cells and other T-cells.
Suppressor T-cells become active after the pathogens are destroyed.
In this way, they turn off the immune response once the infection is under control, preventing damage to healthy tissue.

Memory T-cells stimulate B-cells and killer T-cells to multiply if the same antigen enters the body again.
After an infection, memory T-cells can live for years or even a lifetime, providing immunity to future infections by the same pathogen.