Antigen-presenting cells

Antigen-presenting cells (APCs) are a group of immune cells that mediate the cellular immune response by processing and presenting antigens for recognition by certain lymphocytes such as T cells. Pronunciation: /ˈan(t)əjən prəˈzentɪŋ sɛlz/

Etymology

The term "Antigen-presenting cells" is derived from the function of these cells. "Antigen" is a substance that induces an immune response, and these cells "present" these antigens to T cells.

Types of Antigen-presenting cells

There are three main types of APCs: dendritic cells, macrophages, and B cells. Each of these cells has a different role in the immune response, but all are essential for triggering an effective immune response.

Dendritic cells

Dendritic cells are the most potent of all APCs and are primarily responsible for initiating the primary immune response. They capture, process, and present antigens to T cells in the lymph nodes.

Macrophages

Macrophages are large white blood cells that engulf and digest cellular debris, foreign substances, microbes, and cancer cells in a process called phagocytosis. They also present antigens to T cells to initiate an immune response.

B cells

B cells are a type of lymphocyte that produce antibodies against antigens. They can also act as APCs by presenting antigens to helper T cells, which then stimulate the B cells to produce antibodies.

Function

APCs capture and process antigens, then present them on their surface to T cells. This interaction triggers the T cells to differentiate into effector T cells, which can directly kill infected cells, or helper T cells, which assist in the activation of other immune cells.

Related terms

• Antigen
• Immune system
• Lymphocyte
• T cell
• Dendritic cell
• Macrophage
• B cell
• Phagocytosis

External links

• Medical encyclopedia article on Antigen-presenting cells
• Wikipedia's article - Antigen-presenting cells

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