An antibody, also known as an immunoglobulin, is a large Y-shaped protein used by the immune system to identify and neutralize foreign objects such as bacteria and viruses. The antibody recognizes a unique part of the foreign target, termed an antigen. Each tip of the "Y" of an antibody contains a paratope (a structure analogous to a lock) that is specific for one particular epitope (similarly analogous to a key) on an antigen, allowing these two structures to bind together with precision. Using this binding mechanism, an antibody can tag a microbe or an infected cell for attack by other parts of the immune system, or can neutralize its target directly (for example, by blocking a part of a microbe that is essential for its invasion and survival). The production of antibodies is the main function of the humoral immune system.
Antibodies are produced by a type of white blood cell called a plasma cell.
Antibodies are typically made of basic structural units—each with two large heavy chains and two small light chains. There are several different types
The specificity of an antibody is its ability to discriminate between two different epitopes.
The specificity of antibodies can be so precise that they are able to discriminate between enantiomers of the same molecule
2. What are bispecific antibodies, bispecific complexes? Why are these complexes superior to conventional antibody for diagnosis and therapy?
Bispecific antibodies recognize two distinct targets at the same time. These antibodies might bridge two targets together and present a high-value opportunity for therapeutic gains (such as bringing cancer cells within striking distance of cytotoxic T lymphocytes).
bispecific antibodies are equipped with two different antigen binding sites with the potential to link two epitopes that could be present on two different cell types
monoclonal antibodies have gained momentum as an important source of therapeutic agents. They recognize a single antigen target.
Using BsAbs, it is possible to take advantage of the highly specific binding characteristics of antibodies and combine these with the powerful effector functions of cytotoxic immune effector cells. BsAbs share two different, monoclonal antibody-derived, antigen-recognizing moieties within one molecule. By dual binding, BsAbs reactive with a trigger molecule on an immune effector cell on the one hand and a surface antigen on a tumor target cell on the other are thus able to functionally focus the lytic activity of the immune effector cell towards the target cell.
BsAbs, with a chosen dual specificity for an activation molecule on an immune effector cell and a tumor associ- ated antigen (TAA), allow simultaneous tumor cell binding and effector cell activation through crosslinking [7 – 9].
3. Can antibodies be used for other purposes, other than diagnoses and therapies as presented?
Uses of antibodies. Antibodies have a wide variety of uses.
1. They can be used to immuno-localize a particular antigen in a tissue (immunohistochemistry*). Tissue can be fixed and incubated with the antibodies of interest. These antibodies can then be localized using a 'secondary' antibody coupled to a gold particle or another enzyme that gives a chemical reaction like horse radish peroxidase or beta galactosidase. A secondary antibody is frequently made by generating an immune response to the Fc region of the primary antibody in another species. Thus, if the primary antibody is a mouse IgG, then...