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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 universal structure of antibody includes the constant regions part of the fragment crystallizable(Fc) region of the antibody (shown in dark blue). It also includes the fragment antigen binding which is composed of one heavy and one light chain (shown as L for light and H for heavy).
The immune system identifies and attacks "non-self" external antigens. Antibodies usually do not react with self-antigens due to negative selection of T cells in the thymus and B cells in the bone marrow. [5] The diseases in which antibodies react with self antigens and damage the body's own cells are called autoimmune diseases. [6]
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 ...
Along scFv and Fab fragments, diabodies or bispecific recombinant antibodies are the third major format. [5] Bispecific antibodies combine two different antigen binding specificities within one molecule. [10] The bispecific antibodies are used to crosslink the target molecules with two different cells and mediate direct cytotoxicity. [13] [14]
The final rearrangement of the light chain gene generates immature B cell and mIgM. The process explained here occurs only in the absence of the antigen. The mature B cell formed as RNA processing changes leaves the bone marrow and is stimulated by the antigen then differentiated into IgM -secreted plasma cells.
Antigen presentation stimulates T cells to become either "cytotoxic" CD8+ cells or "helper" CD4+ cells. Antigen presentation is a vital immune process that is essential for T cell immune response triggering. Because T cells recognize only fragmented antigens displayed on cell surfaces, antigen processing must occur before the antigen fragment ...
As IgM antibodies are expressed early in a B cell response, they are rarely highly mutated and have broad antigen reactivity thus providing an early response to a wide range of antigens without the need for T cell help. [5] IgD isotypes are expressed on naive B cells as they leave bone marrow and populate secondary lymphoid organs.