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Professional APCs specialize in presenting antigens to T cells. [5] They are very efficient at internalizing antigens, either by phagocytosis (e.g. macrophages), or by receptor-mediated endocytosis (B cells), processing the antigen into peptide fragments and then displaying those peptides (bound to a class II MHC molecule) on their membrane. [1]
Because T cells recognize only fragmented antigens displayed on cell surfaces, antigen processing must occur before the antigen fragment can be recognized by a T-cell receptor. Specifically, the fragment, bound to the major histocompatibility complex (MHC), is transported to the surface of the antigen-presenting cell, a process known as ...
The discussion that follows now concerns alpha/beta T cells. The TCR (of αβ T-cells) binds a bimolecular complex displayed at the surface of some other cells called an antigen-presenting cell (APC). This complex consists of: a fragment of an antigen lying within the groove of a histocompatibility molecule. The complex has been compared to a ...
The T cells selectively recognize the antigens; depending on the antigen and the type of the histocompatibility molecule, different types of T cells will be activated. For T-cell receptor (TCR) recognition, the peptide must be processed into small fragments inside the cell and presented by a major histocompatibility complex (MHC). [ 12 ]
The T-cell receptor (TCR) is a protein complex found on the surface of T cells, or T lymphocytes, [1] that is responsible for recognizing fragments of antigen as peptides bound to major histocompatibility complex (MHC) molecules.
When foreign proteins enter a cell, they are broken into smaller pieces called peptides. These peptides, also known as antigens, can derive from pathogens such as viruses or intracellular bacteria. Foreign peptides are brought to the surface of the cell and presented to T cells by proteins called the major histocompatibility complex (MHC).
A dendritic cell (DC) is an antigen-presenting cell (also known as an accessory cell) of the mammalian immune system. A DC's main function is to process antigen material and present it on the cell surface to the T cells of the immune system. They act as messengers between the innate and adaptive immune systems. [1]
The fragment antigen-binding region (Fab region) is a region on an antibody that binds to antigens. It is composed of one constant and one variable domain of each of the heavy and the light chain . The variable domain contains the paratope (the antigen-binding site), comprising a set of complementarity-determining regions , at the amino ...