The leucocytes or white globules are cell S produced in the osseous Moelle and present in the Sang, the Lymphe, the lymphoid bodies (ganglia, spleen, amygdala and adenoids and plates of Peyer) and of many conjunctive fabrics of the organization.

The adults in good health have, normally, between 4 billion and 10 billion white globules by Liter blood.

The number of circulating leucocytes increases in the event of infection or by inflammatory reaction: one speaks then about hyperleucocytosis. Among certain patients reached of Leukemia, the white globules can multiply in an excessive way and, to the maximum, cause a syndrome of leucostase.

Types of leucocytes

There exist three big classes of leucocytes: The polynuclear ones (or granulocytes), lymphocytes, and the monocytes (which will become macrophages in fabrics).

Granulocytes (or polynuclear)

One classifies the granulocytes in three categories, according to the coloring of their granules:

• the Mastocytes
• polynuclear the Neutrophile S,
• polynuclear the eosinophilic S,
• polynuclear the Basophilic S.

(See also Granulocyte).

The Lymphocyte S

One distinguishes several categories of lymphocytes.

• the lymphocytes B: they manufacture proteins called specific Anticorps of a Antigène given. This antigen can be carried by an disease-causing agent (bacterium for example) and the antibodies then will help with its destruction. The antibodies can also be directed against an antigen of the " soi" and they are then at the origin of an autoimmune disease (example: antinuclear factors and lupus). There exist also lymphocytes B " mémoire" who allow the maintenance during the time of a reaction immune.
• the lymphocytes T: they are subdivided in three subcategories:
• the cytotoxic lymphocytes T, CD8+ or T8 lymphocytes. They are the effector cells of immunity with mediation cellular. They have a cytotoxic action with respect to cells infected by a virus or cancer cells.
• the auxiliary lymphocytes T (helper), CD4+ or T4 lymphocytes. In fact cells induce and control the immunizing response.
• the lymphocytes T suppressors are also regulating cells.

Monocytes

The Monocyte S and Macrophage S are cells having primarily a function of Phagocytose. The monocytes are cells of blood whereas the macrophages are localized in fabrics.

Functions of the leucocytes or globules white

The Monocyte s/macrophages and the Granulocyte S Neutrophile S are Phagocyte S which introduce the Bactérie S and of the abnormal, infected or died cells.

The lymphocytes are implied in the immune reactions: immunity humorale, related to the production of antibody, and cellular immunity, related to the proliferation of effector cells (cytotoxic lymphocytes T).

The leucocytes observed in blood are in transit. Indeed, the leucocytes pass the major part of their time out of the circulatory system, and patrol in fabrics where the majority of the fights against the agents Pathogène S. the lymphatic ganglia are held also contain many leucocytes.

The leucocytes are manufactured in the osseous Moelle starting from the hematopoietic original cells which are different in precursors myéloïdes (for the polynuclear ones, monocytes and macrophages) or lymphoid (for the lymphocytes). Some Lymphocyte S leave osseous marrow to reach maturity in the lymphatic bodies: Spleen, Thymus, amygdala S, lymphatic bodies of the digestive tract (plates of Peyer) and lymphatic ganglia.

Diseases

The principal diseases affecting the leucocytes specifically are malignant hémopathies: Leukemia acute and chronic, Lymphoma, Myélome, dysgammaglobulinémies malignant (disease of Waldenstrom).

There exist also genetic diseases: Neutropenia congenital severe, syndrome of Shwachman, cyclic neutropenia, granulomatoses septic…

See too

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