Adaptive Immune Response For New Invaders Essay

785 Words Jun 7th, 2015 4 Pages
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 which is specific for a particular antigen. If a B cell binds to its specific antigen, it will multiply and differentiate, which produces large amount of high affinity antibodies.
B cells recognise free antigen in native form. Most antigens are T cell dependent, after binding via antigen-binding Ig receptor, B cell engulfs and internalises antigens. The antigen is then cleaved into fragments and presented on the B cell surface by MHC class II molecules. Presented fragments are recognised by T helper cells which secrete cytokines upon activation. These cytokines provide the second co stimulation signal for B cell activation and proliferation. Thus B cell activation usually requires 2 signals one from binding of the B cell receptor to an…

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