antigen presenting cells

Last reviewed 01/2018

An early event in the mounting of an immune response, is the presentation of foreign antigen to lymphocytes with their subsequent activation. This occurs by the action of various cells listed below:

• macrophages
• epidermal dendritic Langerhans' cells
• Kupffer cells in the Liver
• microglial cells
• microfold M cells of intestinal Peyer's patches

The most common of these is the macrophage, which phagocytoses cell debris and processes antigens from potentially pathogenic organisms.

Antigens are then placed on the surface of the macrophage or other antigen presenting cell, and are presented to lymphocytes, bound to one of the body's own self-recognition antigens.

The latter are products of the major histocompatibility complex, MHC, and on antigen presenting cells are of the class II variety. The combination of foreign antigen bound to MHC class II molecule then leads to lymphocyte activation.

Lymphocytes (such as B cells and T-helper cells) will have antigen presented to them, initiating the adaptive response.

Neutrophils are also antigen presenting cells (APCs).