White blood cells: defense experts
4 10 billion a liter of blood
Leukocytes or more commonly known as white blood cells are the strongest supporters of our organization. These cells are produced in our bone marrow, a tissue located in the heart of our bones. These cells mainly circulate in the bloodstream and lymph. Healthy people account for no less than 4 to 10 billion cells per liter of blood.
An infection was detected after a blood test and if their number increases significantly, it is a sign of infection: this is called leukocytosis.
Differentiation into several categories
Our agency has not developed a form of immune response but several. To meet this demand, white blood cells differentiate into several types of immune cells.
Experts from the phagocytosis
In white cells, three classes are distinguished: monocytes, lymphocytes and granulocytes.
The latter derive their name from the shape of the nucleus and is composed of several lobes suggesting to small grains.
Granylocytes Among these, there are neutrophils. It represents 65% of white blood cells. These neutrophils are produced by bone marrow and have a life span of a few days.
What is their role? They go to the scene of a inflammtion caused by bacteria. They are guided by chemotactic substances emitted by the reaction itself.
Once there, they proceed to phagocytosis. They literally swallowed foreign bodies and destroy them by lytic enzymes, proteins contained in the grains inside the neutrophils. Then all degenerates and is pus.
1 to 3% of WBC
Besides neutrophil granulocytes are also made of eosinophils that represent 1 to 3% of white blood cells. These cells are involved mainly in the destruction of parasites.
They are synthesized in the bone marrow and released into the bloodstream. Like neutrophils, these cells can penetrate the tissue to reach the site of infection. Pathogens, namely by the parasites are then caught by eosinophils that there does not swallow, there is no phagocytosis itself. They stick it and release a basic protein, an enzyme that will completely destroy the parasite membrane and eventually lead to its destruction.
Several places of storage
White blood cells circulate in our body by the blood and lymph to go to meet the intruder, but they can also be stored in specific organs, lymphoid organs. The best known are the tonsils and lymph nodes in the throat, armpits and groin.
Faced with an infection, the number of white blood cells increases which increases the volume of these lymphoid organs. It is a symptom that shows the physician the presence of infection. Now you know why you feels these different places.
Cells responsible for humoral immunity
Lymphocytes are white blood cells responsible for a highly targeted immune response. Among these cells are differentiated B lymphocytes.
These cells are produced in quantity in the bone marrow and acquire maturity. They play a crucial role in humoral immunity, that is to say, the immune response contributing to the production of free antibodies in the blood and lymph.
Your body makes hundreds of thousands of B lymphocytes Among them, there are plasma cells that match the final stage of mature B cells These mature cells produce special molecules called antibodies. They leave in search of a protein produced by foreign cells, the antigen, and get to destroy it. Other B cells possess such antibodies or immunoglobulins directly at their membrane and interact directly with the ‘antigen.
Cells responsible for cell-mediated immunity
These lymphocytes are cells involved in immune response targeted. They will help fight against infection well defined. Unlike other white blood cells, T cells are produced by the thymus (hence the letter T), a lymphoid organ located in the lungs. These cells work in the immune response cell-mediated, everything happens by contact between cells.
As for B cells, several types of T cells at various stages of the immune response. The best known are the lymphocytes T4 and T8. LT4 allow the proliferation of B lymphocytes in fine antibodies; regarding LT8, they allow turning into cytotoxic T lymphocytes to destroy cancer cells or infected by a virus.
The HIV virus attacks the cells
Among all these different immune response pathways, it loses some our Latin. The only thing to remember is that it exists for each type of infection so pathogens, a type of cell to alert ready to act to destroy the intruder.
Still, our immune system is fragile and may become a victim of viruses much stronger than him and more particularly vicious in the image of HIV.
Rather than become stronger than all the immune cells it attacks the pillars of our weapons of defense, namely LT4 and LT8. Without them, most of B-cell proliferation therefore fewer antibodies and activation of cytotoxic T lymphocytes that lyse infected cells. Therefore: the HIV virus has the space to grow slowly in the body.