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A lymphocyte is a type of white blood cell (leukocyte) in the immune system of most vertebrates. [1] Lymphocytes include T cells (for cell-mediated and cytotoxic adaptive immunity), B cells (for humoral, antibody-driven adaptive immunity), [2] [3] and innate lymphoid cells (ILCs; "innate T cell-like" cells involved in mucosal immunity and homeostasis), of which natural killer cells are an ...
Diagram of a lymph node showing lymphocytes. The primary function of lymph nodes is the filtering of lymph to identify and fight infection. In order to do this, lymph nodes contain lymphocytes, a type of white blood cell, which includes B cells and T cells. These circulate through the bloodstream and enter and reside in lymph nodes. [26]
Natural killer cells, also known as NK cells, are a type of cytotoxic lymphocyte critical to the innate immune system.They are a kind of large granular lymphocytes [1] [2] (LGL), and belong to the rapidly expanding family of known innate lymphoid cells (ILC) and represent 5–20% of all circulating lymphocytes in humans. [3]
Lymphocytes are distinguished by having a deeply staining nucleus that may be eccentric in location, and a relatively small amount of cytoplasm. Lymphocytes include: B cells make antibodies that can bind to pathogens , block pathogen invasion, activate the complement system , and enhance pathogen destruction.
In the immune system, circulating cells called lymphocytes form a primary army that defends the body against pathogenic viruses, bacteria and parasites. There are two major kinds of lymphocytes – the T lymphocyte and the B lymphocyte. Among the millions of lymphocytes in the human body, only a few actually are specific for any particular ...
A lymph follicle is a dense collection of lymphocytes, the number, size, and configuration of which change in accordance with the functional state of the lymph node. For example, the follicles expand significantly when encountering a foreign antigen. The selection of B cells, or B lymphocytes, occurs in the germinal centre of the lymph nodes.
Although lymphocytes are usually considered mature, as seen in blood tests, they are certainly not inert. Lymphocytes can travel around the body wherever there is a need. When such needs arise, new rounds of downstream lymphopoiesis, such as cell multiplication and differentiation, may occur, accompanied by intense mitotic and metabolic activity.
Palatine tonsil enlargement can affect speech, making it hypernasal and giving it the sound of velopharyngeal incompetence (when space in the mouth is not fully separated from the nose's air space). [10] Tonsil size may have a more significant impact on upper airway obstruction for obese children than for those of average weight. [11]