What are the cells of the immune system and what do they do?

T-cells of the immune system fight invading molecules directly.
T cells come in two different types, helper cells and killer cells.
They are named T cells after the thymus, an organ situated under the breastbone. T cells are produced in the bone marrow and later move to the thymus where they mature.

Helper T cells are the major driving force and the main regulators of the immune defense. Their primary task is to activate B cells and killer T cells. However, the helper T cells themselves must be activated. This happens when a macrophage, which has eaten an invader, travels to the nearest lymph node to present information about the captured pathogen. The phagocyte displays an antigen fragment from the invader on its own surface, a process called antigen presentation. When the receptor of a helper T cell recognizes the antigen, the T cell is activated. Once activated, helper T cells start to divide and to produce proteins that activate B and T cells as well as other immune cells.

The killer T cell is specialized in attacking cells of the body infected by viruses and sometimes also by bacteria. It can also attack cancer cells. The killer T cell has receptors that are used to search each cell that it meets. If a cell is infected, it is swiftly killed. Infected cells are recognized because tiny traces of the intruder, antigen, can be found on their surface.

B-cells form antibodies that can respond to invading molecules or toxins. The antibodies produced by the B-cells can bind with a potentially damaging molecule or to the surface of a virus or bacteria, thereby targeting it for removal by other immune cells.

Other cells of the immune system includes phagocytic cells, such as macrophages and neutrophils. They also help to remove the debris created from destroying cells and tissue at the site of an infection.

The primary function of white blood cells (leukocytes) is to help heal wounds and fight infections. White blood cells also help protect us against mutated cells (cancer), and from foreign bodies that enter the blood stream (allergens).

As you can see, keeping the cells of the immune system healthy are very important in our bodies enjoying good health, freed from sickness and disease.

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