A type of white blood cell that plays important roles in recognizing and responding to infections, abnormal cells, and other foreign substances.
Lymphocytes are part of the adaptive and innate immune systems and include B cells, T cells, and natural killer (NK) cells. B cells can produce antibodies, while T cells coordinate immune responses or directly destroy infected or abnormal cells. NK cells can recognize and kill certain infected or abnormal cells without the same antigen-specific recognition used by B and T cells.
Lymphocytes circulate through the blood and lymphatic system and are also found in tissues and organs involved in immune defense.
QUICK FACT
“Lymphocyte” is a broad cell category. A CD4 T lymphocyte is one specific type of lymphocyte, not a separate kind of immune system.
COMMONLY CONFUSED WITH
White blood cell: Lymphocytes are one major type of white blood cell. Other white blood cells include neutrophils, monocytes, eosinophils, and basophils.
SEE ALSO