Kinds of Immune Cells

Kinds of Immune Cells : Types of Lymphocytes : Immunity Function

Lymphocytes are a type of white blood cell. They make antibodies and other substances that fight infection and disease. Lymphocytes are found in the blood and throughout the body in lymphatic tissue. They attack viruses, bacteria and other micro-organisms. The white cells of the myeloid lineage include neutrophils, monocytes, eosinophils and basophils. Lymphocytes include T cells, B cells and natural killer cells.

Name	Description
Lymphocyte	T cell (T Lymphocyte)	T cells mature in the thymus, and then gather in lymph nodes and the spleen. T cells directly attack foreign invaders and cancer cells. They direct and control the body’s immune response by signalling other immune system cells to areas where they are needed. They mainly work by making lymphokines (a type of cytokine), which activate other cells and substances. There are types of T cells: • Helper T-Cells(CD4+ TH cells) : activate and regulate T and B cells. Helper T cells stimulate B cells to make antibodies and help killer T cells work better. • Killer T cells (cytotoxic T cells) destroy cancer cells and cells containing foreign substances, such as bacteria or viruses. • Suppressor T cells make substances that help turn off the immune system response. • Gamma delta T cells (γδ T cells) : bridge between innate and adaptive immune responses; as phagocytosis • Regulatory (suppressor) T cells : returns the functioning of the immune system to normal operation after infection; prevents autoimmunity. • Cytotoxic T cells(CD8+ TC cells, Killer T-Cell) : virus-infected and tumor cells.
B cell (B Lymphocyte)	B lymphocytes releases antibodies and assists activation of T cells. B cells mature in the bone marrow, and then move into the lymph nodes and spleen. B cells make proteins (antibodies) in response to foreign substances (antigens). Antibodies recognize and bind to antigens, marking them so other immune system cells can find and destroy them. Each type of antibody can bind to only a specific type of antigen.
Natural Killer (NK) cell	NK Cell can kill virus-infected and tumor cells without prior exposure. NK cells are made in the bone marrow. NK cells attach themselves to cells infected with micro-organisms (such as viruses or bacteria) and to cancer cells. Once attached, they produce chemicals (cytokines) that damage and kill the cells.
Antigen-presenting cells	Dendritic cells	are antigen-presenting cells of the mammalian immune system. (Dendritic cells are a type of white blood cell found in lymph nodes, skin and some organs. They ingest and break an antigen into pieces, then stimulate T cells to destroy the antigen.)
Microphage (Phagocyte)	a small phagocyte, present in neutrophil of blood and lymph, that migrates to tissues in the inflammatory immune response. It ingests small things (as bacteria). Phagocytes are large white blood cells. They surround, swallow and digest foreign substances and damaged cells. (This process is called phagocytosis.) Once these foreign substances are broken down, it is easier for T cells and B cells to recognize and destroy them. There are 2 types of phagocytes: • Monocytes are phagocytes that circulate in the bloodstream. • Macrophages are phagocytes that develop from monocytes that have moved from the blood into tissues or organs, such as the spleen, bone marrow and liver. Macrophages produce cytokines.

Name

Description

Lymphocyte

T cell
(T Lymphocyte)

T cells mature in the thymus, and then gather in lymph nodes and the spleen. T cells directly attack foreign invaders and cancer cells. They direct and control the body’s immune response by signalling other immune system cells to areas where they are needed. They mainly work by making lymphokines (a type of cytokine), which activate other cells and substances.
There are types of T cells:
• Helper T-Cells(CD4+ TH cells) : activate and regulate T and B cells. Helper T cells stimulate B cells to make antibodies and help killer T cells work better.
• Killer T cells (cytotoxic T cells) destroy cancer cells and cells containing foreign substances, such as bacteria or viruses.
• Suppressor T cells make substances that help turn off the immune system response.
• Gamma delta T cells (γδ T cells) : bridge between innate and adaptive immune responses; as phagocytosis
• Regulatory (suppressor) T cells : returns the functioning of the immune system to normal operation after infection; prevents autoimmunity.
• Cytotoxic T cells(CD8+ TC cells, Killer T-Cell) : virus-infected and tumor cells.

B cell
(B Lymphocyte)

B lymphocytes releases antibodies and assists activation of T cells. B cells mature in the bone marrow, and then move into the lymph nodes and spleen.
B cells make proteins (antibodies) in response to foreign substances (antigens). Antibodies recognize and bind to antigens, marking them so other immune system cells can find and destroy them. Each type of antibody can bind to only a specific type of antigen.

Natural Killer (NK) cell

NK Cell can kill virus-infected and tumor cells without prior exposure. NK cells are made in the bone marrow.
NK cells attach themselves to cells infected with micro-organisms (such as viruses or bacteria) and to cancer cells. Once attached, they produce chemicals (cytokines) that damage and kill the cells.

Antigen-presenting cells

Dendritic cells

are antigen-presenting cells of the mammalian immune system.
(Dendritic cells are a type of white blood cell found in lymph nodes, skin and some organs. They ingest and break an antigen into pieces, then stimulate T cells to destroy the antigen.)

Microphage
(Phagocyte)

a small phagocyte, present in neutrophil of blood and lymph, that migrates to tissues in the inflammatory immune response. It ingests small things (as bacteria).
Phagocytes are large white blood cells. They surround, swallow and digest foreign substances and damaged cells. (This process is called phagocytosis.) Once these foreign substances are broken down, it is easier for T cells and B cells to recognize and destroy them.
There are 2 types of phagocytes:
• Monocytes are phagocytes that circulate in the bloodstream.
• Macrophages are phagocytes that develop from monocytes that have moved from the blood into tissues or organs, such as the spleen, bone marrow and liver. Macrophages produce cytokines.

Antigens and antigen-presenting cells

Antigens are substances on the surface of cells. When T cells or antibodies recognize antigens, they trigger an immune response. Antigens can be anything the body recognizes as foreign, including bacteria, viruses, cancer cells or other invaders that can cause infection or disease.
Antigen-presenting cells (APCs) surround the foreign invaders. Then the APCs show (present) the antigens from these foreign invaders to T cells and B cells. The T cells and B cells can then recognize and respond to the invaders.

Source : http://www.cancer.ca

NK cells and T cells rates of Human peripheral blood lymphocyte

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