Classification of immune active cells

Immune living cells are cells that participate in immune responses. They can undergo corresponding changes when stimulated by antigens, thereby forming immune effector substances, which also include lymphocytes, monocytes, granulocytes, macrophages, etc. It plays a very good role in eliminating viral infections and preventing tumors. Once the immunity decreases, the number of immune cells will also decrease accordingly.

definition

Immunocompetent cells (ICC) are lymphocytes that can be activated, proliferate, differentiate and produce specific immune responses when stimulated by antigens. They are called antigen-specific lymphocytes or immunocompetent cells, namely T lymphocytes and B lymphocytes. In addition, lymphocytes also include K cells, NK cells, etc., which are also immune active cell groups.

Lymphoid cell classification

① Cytotoxic T cells or killer T cells transformed from T cells: after receiving antigen information, they can directly produce a killing effect on target cells;

② Natural killer cells (NK cells): A type of monocyte present in humans and mice that can spontaneously kill target cells. When exerting its killing effect, it does not require prior antigen stimulation nor the participation of specific antibodies, so this killing effect is called spontaneous lymphocyte-mediated cytotoxicity. It plays an important role in eliminating virus-infected cells, tumor cells, and bone marrow transplant cells;

③ Antibody-dependent cytotoxic cells: also known as killer cells (K cells). They do not need to be sensitized with specific antigens in advance when killing target cells. However, during the killing process, antibodies that can specifically bind to target cells must be present, because K cells have Fc receptors for antibody IgG on their surface. Only after specific antibodies bind to target cells can K cells exert their killing effect. Therefore, these cells that have a killing effect are called antibody-dependent cytotoxic cells (ADCC). K cells in the body mainly kill virus-infected cells and tumor cells.

The mononuclear phagocyte system is a general term for large monocytes that exist in the blood, have a high degree of phagocytic function, and can quickly clear the ingested substances, as well as free and fixed macrophages in tissues. Macrophages also have many receptors, such as the Fc receptor of immunoglobulin IgG, the complement C3 receptor, and receptors that can bind to lymphocytes, certain particles, phytohemagglutinin (PHA), and macrophage migration inhibitory factor (MIF). Therefore, they play an important role in exerting biological effects such as phagocytosis, pinocytosis, cell recognition, and antigen binding. Macrophages not only participate in the body's nonspecific immunity, but also participate in immune surveillance and produce macrophage factors to regulate specific immune responses.