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(lymphocytes)

Lymphocytes are a type of leukocyte (white blood cell) included within the agranulocytes. Leukocytes are smaller (between 7 and 15 microns), and represent from 24 to 32% of the total in the peripheral blood. Have a large spherical nucleus which stained violet-blue and the cytoplasm is often seen as a peripheral ring of blue. They have a thin rim of cytoplasm containing some mitochondria, free ribosomes and a small Golgi apparatus. Lymphocytes are cells
senior in the immune system, mainly responsible for the specific or acquired immunity.
These cells are located mainly in the lymphoid organs. Have receptors for specific antigens and, therefore, can recognize and respond to them present. Finally, lymphocytes are responsible for antibody production and destruction of abnormal cells. These responses occur within the lymphoid organs, which, for the purpose, should provide an enabling environment for efficient interaction between lymphocytes, macrophages and foreign antigen. The main cause of stress is increasing.

Lymphocyte (SEM).

Lymphocyte is showing large nucleus (microscope Optical).

Types:

Lymphocytes are difficult to classify cells according to their morphology, so they resorted to the use of "CD's" or differentiation antigens for characterization.
B lymphocytes (bursodependientes) are responsible for humoral response, ie production of antibodies, proteins (immunoglobulins) that attach to a specific antigen (which recognize uniquely). They are able to lipids, proteins, carbohydrates.
T lymphocytes (thymus-dependent) protein antigens detect molecules associated with the main complex histocompatibility complex (MHC 0 CMH)
CD4 + lymphocytes or T4 cells. Recognize antigens presented by MHC-II. Lymphocytes are also called "helper" or partners involved in the immune synapse.
cytotoxic T lymphocytes and CD 8 + lymphocytes. Recognize peptides presented by MHC-I and have lytic capacity.
natural killer cells, Natural Killer (NK) or large granular lymphocyte. They have characteristic markers, involved in innate immunity are able to recognize "self" also have lytic properties.

Transmigration:

Step N ° 1 - Adhesion and rotation: For the lymphocyte to adhere to the endothelial cell exceed the shear forces created by blood flow. This is achieved by a force of attraction between guidance receptors (integrins and L-selectin) and their ligands on the vessel wall that operates through microvilli on the surface of lymphocyte. After this process of adhesion, the lymphocyte broken along endothelial cells and integrins VLA-4 or LpAm-1 on lymphocytes, bind to their ligands on endothelium.
Step N ° 2 - Activation of LFA-1 and flattening: This process leads to the activation and recruitment of the integrin LFA-1 to the lymphocyte surface is not hairy. This integrin binds very strongly to ICAM-1 and ICAM-2 on endothelial cells and intimate contact causes the lymphocyte to flatten.
Step N ° 3 - diapedesis: The flattened-cell interaction is now using the LFA-1-ICAM and the member of the immunoglobulin superfamily PECAM-1 (endothelial adhesion molecule to platelet CD31, not only present in platelets) to way through the endothelial cells and tissue, in response to a chemotactic signal.