Lymphocyte

A Lymphocyte is a type of white blood cell in the vertebrate immune system. Under the microscope, lymphocytes can be divided into large lymphocytes and small lymphocytes. Large granular lymphocytes include natural killer cells. Small lymphocytes consist of T cells, B cells and cell-mediated immune cells.

Overview

Lymphocytes are the cornerstone of the adaptive immune system, which is responsible for the body's immunity. They are derived from common lymphoid progenitors in the bone marrow. They are found in the blood and lymph, and in lymphoid organs such as the lymph nodes, spleen, and thymus.

Types of Lymphocytes

There are three main types of lymphocytes: B cells, T cells, and natural killer (NK) cells.

B Cells

B cells are involved in the humoral immune response, which targets pathogens loose in blood and lymph. B cells mature in the bone marrow.

T Cells

T cells are involved in the cell-mediated immune response, which targets infected cells. T cells mature in the thymus.

Natural Killer Cells

Natural killer cells are a part of the innate immune system and play a major role in defending the host from both tumors and virally infected cells.

Function

Lymphocytes play a central role in the immune response. They recognize and respond to foreign antigens, produce antibodies, and remember past pathogens.

See Also

• Immune system
• White blood cell
• Antigen
• Antibody

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