Lymphocytes

Lymphocytes are immune cells that include B cells, T cells, and natural killer cells. These groups perform different tasks in recognizing threats and coordinating or carrying out immune responses. They occur in blood and in lymphoid tissues, where many of their interactions with other immune cells take place .¹

B and T cells are central to adaptive immunity, which recognizes particular molecular targets called antigens. Activated B cells can become plasma cells that release antibodies. Some T cells help activate other immune cells, while others kill infected cells. Individual B and T cells carry receptors with different specificities, allowing their combined populations to recognize a wide variety of targets .¹

Natural killer cells belong to innate immunity and can attack certain infected or abnormal cells without the same antigen-specific receptor system used by B and T cells .¹