Lymphocyte B
The lymphocytes B or cells B , also called bursocytes , are Lymphocyte S which have as a role to manufacture Immunoglobuline S called Anticorps: they are thus responsible for immunity humorale. To be active, others globules white such as Macrophage S, must to present them fragments of Antigen, so that they are transformed into Plasmocyte S. These lymphocytes have much more blisters of Golgi, which make it possible to manufacture antibodies in mass, in order to neutralize the antigens effectively. The plasmocytes are thus lymphocytes B activated and able to produce antibodies directed against the antigen activator.
The lymphocytes B are cells taking part in the specific immunizing response, i.e., that a lymphocyte B given can react only against one precise antigen. This specificity is given by BCR (for B-concealment receptor, in French: receiver of the cells B), also complexes membrane similar to TCR lymphocytes T. BCR is resulting from a Recombinaison V (D) J.
the cells B are lymphocytes which play a great part in the Immunité humorale (in opposition to cellular immunity). " B" is the abbreviation of the purse of Fabricius, a body of the birds, in which the cells B become ripe, and not that of osseous English marrow (: bone marrow ) in which the cells B are produced at all the other vertebrate ones.
The human body produces hundreds of thousands of the types different of cells B, and each type has on its membrane a particular BCR, which will bind to a particular antigen; at every moment million cells B circulates in blood and the lymph, without producing antibody. There are several types of cells b:
- the naive cells B, which never yet met their antigen of predilection;
- the Plasmocyte S secrete Anticorps which take care of the destruction of the Antigène S while binding to those so that they become easier preys for the Phagocyte S;
- the cells B with memory are formed specifically against the antigens met at the time of the primary immunizing response; as they can live a long time, these cells can react quickly during one second exposure to their specific antigen.
The Immunité humorale (the creation of antibody circulating in the plasma and the Lymph) imply the Activation cells B. cellular activation can be measured by means of technique ELISPOT or of cytometry in flow (FACS) which can determine the percentage of cells B secreting any particular antibody.
The cells B are characterized on the plan immunohistochimic by the presence of CD79b, (transmembrane chain of immunoglobine which is component BCR on their plasmic membrane.
Susumu Tonegawa obtained the Nobel Prize of physiology or medicine, in 1987, to have shown how the cells B create an enormous diversity of antibody at the beginning of a small number of genes.
See too