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| Question | Answer |
| what is the purpose of the effector section of the antibody | allows interaction with compliment or other molecules |
| clinically why are effecter regions of the B cell useful? | we can attach drugs or target things to the effector section of the antibody |
| how do we know that antibodies are a really important aspect of the immune syste, | diseases which decrease the number/ effectiveness of antibodies are very severe |
| why are huge deficiencies in antibody numbers very rare? | - because this will kill people off v quickly - meaning any congenital issue like this would be removed from the gene pool before reproductive age |
| what 2 main receptors are found on B cells which bind to antigen? | - the B cell receptor - the immunoglobulin itself |
| what 2 cell types can B cells differentiate into? | plasma cells and memory B cells |
| what is the purpose of B cells havingMHC2 receptors on their membranes? | allows the B cell to activate CD4+ T helper cells which will aid in the B cell maturation |
| give a few important mechanisms used ny antibody which aid the immune syste, | - binds to bacterial toxins - labelling the surface of pathogens for destruction by macrophages etc - compliment activation |
| where are B cells first made and then whre are they made in adults? | - first made in foetal livers - then made ion Bone marrow |
| where does the majority of B cell development happen? | in the bone marrow |
| what are the 3 main types of B cellls (not differentiated cell) | - B1 B cells - Follicular B cells - Marginal Zone antibodies |
| why does B cell activity need to be highly regulated? | to prevent autoimmunity and cancer |
| give the life cycle of a B cell | - B stem cell in bone marrow proliferates and differentiates into Naive B cell - B cell binds to complimentry antigen to activate it - differentiates into plasma or memory B cell |
| what is the first step in production of. B cell in the bone marrow? | B cell precursor rearranges its immunoglobulin genes randomly to give a random receptor |
| how is autoimmunity prevented in B cell development in the bone marrowq? | - negative selection - host cell antigens are presented to the B cell receptors, if they bind then the B cell is killed off |
| where does negative selection happen for a B cell? | in the bone marrow |
| what chain of the B cell receptor is made first? | the heavy chain |
| specifically which receptor genes are rearranged during heavy chain development? | D-J and V-DJ genes |
| is the light chain formed by the time the heavy chain is presented on the cell surface? | no - makes heavy chain which is presented on a surrogate light chain to the surface... then goes to make the light chain |
| specifically which light chain genes are rearranged during receptor development | V-J genes |
| what happens to the light chain once its been formed? | its incorporated into the heavy chain to make a complete BCR |
| what 2 antibodies are present on the first mature B cell | IGM and IGD |
| once both heavy and light chains are formed what happens to gene rearangement | its stopped |
| what is the success rate of BCR gene rearangement? | 70% failure rate per chain recombination |
| how does the B cell prevent further gene rearrangement after the BCR is formed? | preventing RAG expression and function (RAG is gene responsible for rearrangement) |
| are both inherited chromosomes recombined for BCR's? | yes but one at a time |
| what is the term for stopping gene rearrangement once the BCR has been formed? | allelic exclusion |
| what are the 2 light chains called? | kappa and lambda |
| what is the ratio of Kappa : Lambda in humans? | 2-3:1 |
| why does the cell use all potential genes for BCR development? | raises chance of making successful BCR |
| what cells in the bone marrow do B cells develop on | stromal cells |
| what do stromal cells do to aid B cell devlopment | - give contact dependant support - release cytokines |
| what are the 2 outcomes if a B ell recognises host cell receptors? | apoptosis receptor rearrangement |
| in B cells does positive or negative selection happen first? | negative selection happens before positive selection (remove host targeting cells first) |
| how does the B cell undergo positive selection? | - if there is need for the B cell itll be given a survival signal - if not itll die |
| which chain is rearranged in a pro B cell and which is rearranged in a pre B cel? | pro-B cell = heavy chain rearrangements pre-B cell = light chain rearrangements |
| what immunoglobulin is presented by immature B cells? | IGM |
| what antibodies do mature B cells present? | any of the random ones + IGD |
| give the difference in receptors from resting B cells and plasma cells | - resting B cells: lots of MHC 2, surface antigen but not IG secretion - plasma cellss: have low surface IG, has no MHC2, has high rate of IG secretion |
| out of resting B cells and plasma cells which can undergo somatic hypermutation and isotype switching? | - only the resting B cell - this is why the plasma cell loses its MHC2 receptors |
| why does the resting B cell have lots of surface BCR's | to increase chance of detecting pathogen antigen |
| explain "Plasma cells are terminally differentiated" | they cant undergo isotope switching or somatic hypermutation, they are finished maturing |
| what are the 2 mechanisms of Bc ell antibody responses | - T cell dependant activation - T cell independant activation |
| explain T cell independant | - no T cell driven maturation - some IGM and IGG but little fine tuning of the receptors to the pathogen |
| explain T cell dependant antibody response | recruiting T cells allows cross talk and fine tuning of the antibdoy response |
| which out of the 2 types of B cell antibody responses produced Memory B cells | T cell dependant antibody responses gives memory B cells |
| what is the benefit of T cell dependant antibody response | the antibodies are much more specific and gives a much more long lived response |
| why are vaccination programs given to young children? | because their T independant responses are poor |
| where does T dependant antibody response begin? | in germinal centres such as in lymphoid tissue and the spleen |
| what are the 2 sections of germinal centres | - the follicle - the T zone |
| what are found in the follicles and the T zones of germinal centres? | - T zones are just T cells - follicles are B cells |
| give the full life cycle of a B cell | |
| another helpful diagram | |
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