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Almost all cell types can present antigens in some way. They are found in a variety of tissue types. Dedicated antigen-presenting cells, including macrophages, B cells and dendritic cells, present foreign antigens to helper T cells, while virus-infected cells (or cancer cells) can present antigens originating inside the cell to cytotoxic T ...
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 diseases in which antibodies react with self antigens and damage the body's own cells are called autoimmune diseases. [6] Vaccines are examples of antigens in an immunogenic form, which are intentionally administered to a recipient to induce the memory function of the adaptive immune system towards antigens of the pathogen invading that ...
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]
As with B cells, each type of T cell recognizes a different antigen. Killer T cells are activated when their T-cell receptor binds to this specific antigen in a complex with the MHC Class I receptor of another cell. Recognition of this MHC:antigen complex is aided by a co-receptor on the T cell, called CD8. The T cell then travels throughout ...
T cells that bind (via their T cell receptor) to self antigen (presented by dendritic cells on MHC molecules) too strongly are induced to die. The second type of immunological tolerance is peripheral tolerance. Some self reactive T cells escape the thymus for a number of reasons, mainly due to the lack of expression of some self antigens in the ...
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 ...
This is the molecule which is loaded with the specific antigen. MHC class I are found on all cells and stimulate cytotoxic T cells (CD8 cells), and MHC class II are found on APCs and stimulate helper T cells (CD4 cells). It is the specific antigen or epitope that is loaded into the MHC determines the antigen-specificity. The peptide-loaded MHC ...