Adaptive Immune Response

The main features of the adaptive immune response is to adapt its response to new invaders and its ability to specifically recognise and remember an invader. B cells are used in the humoral division of the adaptive immune system. Each B cell has a different antigen-binding specificity. Only one B cell is activated per antigen but the activated B cell can differentiate and secrete many antibodies with the same specificity for the original antigen.
B cells express specific antigen receptors (immunoglobulin molecules) on their cell surface during their development and, when mature in the bone marrow, secrete soluble immunoglobulins (antibodies) into the extracellular fluids. Each B cell is genetically programmed to express a surface receptor
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Plasma cells then secrete antibodies (IgM) with same specificity (same hypervariable regions) as the original B cell receptor (i.e. primary response). B cells then switch the class of antibody made from IgM to other classes. B cells further mutate their Ig hypervariable region gene sequences, to generate antibodies with higher affinity for antigen. These B cells with immunoglobulin receptor will then proliferate further with high affinity antibodies this is known as affinity maturation. B cells with high affinity differentiate into long-lived memory B cells and activated rapidly upon subsequent antigen exposure to differentiate into plasma cells to generate high affinity antibodies (secondary …show more content…
They can be attached to the B cell receptor as an immunoglobulin receptor or in secretory form in fluid. Different antibodies will have different structure of hypervariable regions, which will produce different shapes of antigen-binding sites. Variation in shape of antigen binding sites can increase affinity. Any given antigen has different epitopes that are recognised by a different antibody. The hypervariable regions are mutated for production of high affinity antibodies. Immunoglobulin genes undergo a process of somatic hypermutation. Somatic hypermutation is important for the generation of high affinity antibodies, it introduces point mutations at a very high rate into variable regions of the rearranged heavy and light chain genes. This results in mutated immunoglobulin molecules on the surface of the B cells. Somatic recombination involves gene segments of the heavy and light chains’ variable, diversity and joining regions. The mechanism entails multiple V genes recombining with D and J segments, VJ and VDJ recombination and addition of N and P nucleotides (V-D-J joining), transcription and RNA processing in three B cell clones in germline DNA. Endonuclease cuts randomly after one D and before one J and then after one V and before DJ. The free ends are ligated together to form a functional gene; this is

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