Humoral b-cells
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| MCD – Immunology 5 - B-lymphocytes
Anil Chopra
There are 2 types of adaptive response
B  - cells are produced and mature in the bone marrow and travel to the lymphoid tissue in the circulation. They form part of the humoral adaptive immune response in the production of antibodies and memory cells. They only become activated by antigens. Mature B cells contain receptors specific for certain antigens. The B-cell antigen receptor is made up of 3 parts:
T  he mIg part of the receptor contains the binding site (which binds to the antigen) known as the antigenic determinant or epitope. There are thousands of receptors on the surface of each B cell. 
We have a very large number of different antigens we can possibly encounter and so we have a very large number of different B-cell receptors; this is called the repertoire. This diversity is generated by the way in which the B-cell receptor is synthesised. Instead of there being one main functional gene that codes for the production of the B-cell receptor, there are many different genetic fragments darted about the genome on different chromosomes. When the B-cell is maturing, these gene segments are brought together in a random order and so a different B-cell receptor is synthesised in each cell. This is known as immunoglobulin gene rearrangement.
When antigens are encountered, there are 2 main events that take place. The first is clonal selection. This is where the B-cell receptor first encounters the antigen; the antigen has “selected” that particular B-cell because of its specific receptor. However, in order for activation to occur their needs to be an accessory signal, either from
In thymus independent activation, the B-cells “express” the antigens on their surface so that T-helper cells can bind to them and bring about the second response: Clonal expansion – this is where at particular B-cell makes many copies of itself – clones. These differentiate into memory cells and plasma cells. The plasma cells are the sites of: Antibody production – production of soluble B-cell receptors in response to the antigen. 
When the T-helper cells are activated, they release cytokines. Each of the different cytokines stimulates/inhibits the production of the different Ig isotypes. The memory cells that are produced have a long life span and form the basis of immunological memory. This means that if the person encounters the same antigen again, the secondary immune response will occur. In this response, antigen production is a lot faster and more IgG is produced. 
without antigenic stimulation and secretes antibodies which are indistinguishable from normal antibody = myeloma proteins Directory: exec exec -> List of accessible executive records exec -> Executive Board of the United Nations Development Programme, the United Nations Population Fund and the United Nations Office for Project Services exec -> Annex 1: Terminology Used in the Gender Equality Strategy exec -> Executive Board of the United Nations Development Programme, the United Nations Population Fund and the United Nations Office for Project Services exec -> United Nations Development Assistance Framework (undaf) 2017-2021 Mongolia Joint work, shared gains Draft as at exec -> Country: Bangladesh country programme performance summary1 exec -> Country: Thailand country programme performance summary1 exec -> Executive mpa 2014 Faculty & Practitioner Biographies 2014-2015 exec -> State of new mexico bill richardson exec -> Executive summary Download 10.78 Kb. Share with your friends:
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utline the differences in antibody production during primary and secondary immune responses.
