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An epitope , also known as antigenic determinant , is the part of a macromolecule that is recognized by the immune system, specifically by antibodies
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Most epitopes recognized by antibodies or B cells can be thought of as three-dimensional surface features of an antigen molecule; these features fit precisely and thus bind to antibodies
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In order to fit to the epitopes the Ab rearranges its shape for a best fit forming hypervariable loops also called complimentary determining regions'' (CDR's)
 Ab’s will only recognize the 3-D shape of the epitope
 In these loops the part of the Ab that fits is pushed towards the Ag and the parts that don’t fit are pushed out
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An idiotope is the unique set of antigenic determinants of the variable portion of an antibody.
In other words it is the part of the Ab that hooks up to the epitopes of the Ag.
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Each antibody would have multiple idiotopes; and the sum of these individual idiotopes is termed the idiotype of the antibody
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Idiotopes belong to the FAB region of the Ab
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Only a small amount of the variable domain of the FAB is responsible to joining to the epitopes
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15-20 aa form the tips of the 6 hyppervarialbe loops (3 from light chain and 3 from heavy chain)
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Monoclonal antibodies (mAb or moAb) are monospecific antibodies that are identical because they are produced by one type of immune cell that are all clones of a single parent cell.
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Monoclonal antibodies are typically made by fusing myeloma cells with the spleen cells from a mouse that has been immunized with the desired antigen.
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Unfused normal spleen cells cannot grow indefinitely because of their limited life span. However, hybridoma cells are able to grow indefinitely because the spleen cell partner supplies HGPRT and the myeloma partner is immortal because it is a cancer cell. The fused hybrid cells are called hybridomas.
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This mixture of cells is then diluted and clones are grown from single parent cells. The antibodies secreted by the different clones are then tested for their ability to bind to the antigen
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When the hybridoma cells are injected in mice they produce tumors containing an antibody-rich fluid called ascites fluid.
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Once monoclonal antibodies for a given substance have been produced, they can be used to detect
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 the presence and quantity of this substance, for instance in a Western blot test (to detect a protein on a membrane) or an immunofluorescence test (to detect a substance in a cell).
One possible treatment for cancer (especially breast cancer) involves monoclonal antibodies that bind only to cancer cell-specific antigens and induce an immunological response against the target cancer cell.
Such mAb could also be modified for delivery of a toxin, radioisotope, cytokine or other active conjugate; it is also possible to design bispecific antibodies that can bind with their Fab regions both to target antigen and to a conjugate or effector cell. In fact, every intact antibody can bind to cell receptors or other proteins with its Fc region.