Mononuclear, nonphagocytic leukocyte that originates from stem cells and differentiates in lymphoid tissue (as of the thymus or bone marrow). It is the typical cellular elementsof lymph and constitutes 20–30% of the white blood cells of normal human blood. Divided on the basis of ontogeny and function into two classes: B, T lymphocytes, responsible for humeral and cellular immunity, respectively.
A small white blood cell (leucocyte) that plays a large role in defending the body against disease. Lymphocytes are responsible for immune responses. There are two main types of lymphocytes: B cells and T cells. Lymphocytes secrete products (lymphokines) that modulate the functional activities of many other types of cells and are often present at sites of chronic inflammation.
A white blood cell. Lymphocytes have a number of roles in the immune system, including the production of antibodies and other substances that fight infection and diseases.
A type of cell found in the blood, spleen, lymph nodes, etc. of higher animals. They are formed very early in fetal life, arising in the liver by the sixth week of human gestation. There exist two subclasses of lymphocytes: B lymphocytes and T lymphocytes. B lymphocytes make antibodies (immunoglobins) of which there are five classes: IgM, IgA, IgG, IgD and IgE. The antibodies circulate in the bloodstream. T lymphocytes recognize and reject foreign tissue, modulate B cell activity, kill tumor cells, and kill host cells infected with virus. T-lymphocytes are also called T cells.
A type of white blood cell that is produced in bone marrow. Lymphocytes are present mainly in lymph and blood. Lymphocytes are part of the immune system and respond to fight infections and cancer.
One of two types (B cells and T cells) of leukocytes (white blood cells) found in blood, lymph, and lymphoid tissue.
White blood cells that can produce antibodies and interferon.
A type of mature leucocyte or white blood cell formed by the lymph nodes and concerned with the production of antibodies.
Agranulocytic leukocyte (white blood cell) that normally makes up about 25% of the total white blood cell count but increases in the presence of infection. Lymphocytes occur in two forms: B cells, the chief agents of the humoral immune system, which recognize specific antigens and produce antibodies against them; and T cells, the agents of the cell-mediated immune system, which secrete immunologically active corn-pounds and assist B cells in their function.
A type of white blood cell that is the basic functional unit of the body’s immune system, which fights disease-causing microorganisms that invade the body.
A variety of white blood cell (leukocyte), present also in the lymph nodes, spleen, thymus gland, gut wall, and bone marrow. With Romanovsky stains, lymphocytes are seen to have dense nuclei with clear pale-blue cytoplasm. Lymphocytes with scanty cytoplasm are small lymphocytes; those with abundant cytoplasm are large lymphocytes. There are normally 1.5-4.0 X 10⁹ lymphocytes per liter of blood. They are involved in ‘immunity and can be subdivided into B-lymphocytes, which produce antibodies, and T-lymphocytes, which are involved in graft rejection, etc.
A variety of white blood cell produced in the lymphoid tissue and lymphatic glands of the body. They contain a simple, rounded nucleus. They play an important part in the production of antibodies, and in the rejection of transplanted organs such as the heart. This they do in two different ways: what are known as B-lymphocytes produce antibodies, while T-lymphocytes attack and destroy antigens directly. The latter are known as T-lymphocytes because they are produced by the thymus gland. Their numbers are increased in tuberculosis and certain other diseases. Such an increase is known as lymphocytosis.
A white blood cell responsible for much of the body’s immune protection. Fewer than 1% are present in the circulating blood; the rest lie in the lymph nodes, spleen, and other lymphoid organs, where they can maximize contact with foreign antigens.
Lymphocytes are white blood cells that are an important part of the body’s immune system.
A type of white blood cell. Lymphocytes have a number of roles in the immune system, including the production of antibodies and other substances that fight infection and diseases.
A type of white blood cell that is part of the immune system. Lymphocytes can be subdivided into two main groups: B-lymphocytes, which originate in the bone marrow and produce antibodies; T-lymphocytes, which are produced in the bone marrow and mature in the thymus. Helper T-lymphocytes heighten the production of antibodies by B-lymphocytes; suppressor T-lymphocytes suppress B-lymphocyte activity and seem to be in short supply during an MS exacerbation.
The type of white blood cell that carries out most of the immune system’s functions.
A category of immune system cells that includes the natural killer cells, the T cells, and the B cells.
A category of leukocytes that plays a crucial role in the immune reaction against foreign substances known as antigens.
Lymphocytes are a type of white blood cell vital to the immune system, as they battle infections and cancer. The two main kinds of lymphocytes are B-lymphocytes and T-lymphocytes.
B-lymphocytes generate immunoglobulins or antibodies, which are proteins that bind to antigens found on the surfaces of bacteria. This binding initiates a sequence that results in the bacteria’s elimination.
T-lymphocytes are divided into two primary categories based on the antigens on their surfaces. The CD8 group encompasses both killer (cytotoxic) and suppressor cells, while the CD4 group consists of helper cells. Killer T-lymphocytes target abnormal cells, such as cancer cells, virus-infected cells, or those in transplanted tissue, and release substances that aid in destroying these cells. Suppressor T-cells modulate and reduce the immune response. On the other hand, helper T-cells amplify the functions of killer T-cells and B-cells and play a central role in directing the immune response.
Certain B- and T-lymphocytes don’t directly engage in immune reactions but act as repositories for previously encountered antigens. These lymphocytes form when immune cells react to an infection, retaining knowledge on how to address that particular threat. After the immune response concludes, these memory cells remain in the body, primed to facilitate future immune reactions to the same infection.