front 1 Lecture 3 1/23/24 | back 1 Antibody structure unplugged: antigen specificity and functionality |
front 2 antibodies are key to adaptive immunity and the success of vaccines | back 2 how were antibodies discovered? what are antibodies? |
front 3 serum therapy for diptheria | back 3 emil von behring - awarded first nobel prize 1901 for discovering serum therapy for diptheria
First scientific drug discovery: 1901 for diptheria If transfer serum, from infected individual, the peoplewho received it did not die Big deal – was miracle drug at the time Lethal disease Know serum contains proteins that can be protective if exposed to pathogen |
front 4 blood serum injection into child sickened with diptheria | back 4 pic |
front 5 story pf serum therapy | back 5 doctors and nurses restrain ernest booth, one of the 35,000 children who took part in a gamma globulin trial during polio outbreak in houston texas, 1953 |
front 6 convalescent plasma therapy 2020 | back 6
Fast forward to today Serum presented as novel therapy for covid when used (plasma therapy) - extensively used in early days of covid, helped many people - eventually some companies made antibodies instead of serum, that neutralized the virus - manufactured antibodies, then used as a treatment |
front 7 B cell module | back 7 lesson 1 01/23/24 lecture outline A.Seamless transition of innate to adaptive immune response B.Types of Adaptive Immunity C.Clonal selection theory: Explains the concept of one B cell clone one antibody D.Membrane-bound antibody is B cell antigen receptor (BCR) [T cell antigen receptor (TCR) is made only as membrane bound] What is antibody before becomes antibody? A membrane bound molecule before it becomes an effector secreted protein (antibody) TCR is also membrane bound – is never secreted |
front 8 progression of an immune response | back 8 innate -> adaptive immunity picture TCR secreted Transition innate -> adaptive Innate see pathogen, sample it, kill as much as can Dendritic cells educate T lymphocytes about antigen (show it to T cell) and T cell activated by it? B and T cells slow – typically few in number few a specific antigen (10, 50, maybe 100) at first - then clonal selection occurs and they must make more |
front 9 cont. | back 9 dendritic cell activate T cell antibody producing cells = plasma cells |
front 10 humoral and cell mediated | back 10 humoral (antibody mediated) (B cell)
cell mediated (T cell)
B cells can bind pathogens directly Humoral bc antibodies secreted Cell mediates bc cannot directly eliminate pathogen |
front 11 holy grail of adaptive immune response | back 11 principles of adaptive immunity antibody X cell make antibody + clear infection B cells left over are memory cells
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front 12 edward jenner story | back 12 Cowpox was discovered to give immunity from smallpox - where word vaccination comes from |
front 13 Q1. Why is the secondary antibody response greater and faster than the primary? | back 13 no data |
front 14 B cells and T cells recognize antigens via antigen receptors | back 14 BCR (B cell receptor)
TCR (T cell receptor)
both have variable region (antigen binding site) and constant region closer to base Exam question about this stuff? B cells work by shooting their antibodies T cell receptors are not effector molecules – it is never secreted even though the T cells are effector cells |
front 15 antibody is made up of two distinct polypeptides: heavy chain (HC) and light chain (LC) | back 15 membrane bound IgM is also called B cell receptor (BCR) membrane bound is the B cell antigen receptor
before antibodies come about, how does BCR become an antibody molecule?
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front 16 properties of antibodies and T cell receptors | back 16 BCR has unique situation
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front 17 BCR transmits intracellular signaling via associated Iga/Igb proteins | back 17 BCR signaling changes the biology of B cell -> activation -> proliferation - antigen binding brings more than 1 BCR together -> congregation (crosslinked B cell) allows phosphorylation - motive in associated proteins – they must change in order to get signal to multiply and make millions of cells - ITAM (the motive) – change in binding site may cause this change inside (but we do not know) - discovered biochemical changes altered the state of signal transduction in the lymphocyte -> initiate multiplication of the cell to make many B cells that have the binding specificirt of the SAME antigen Clonal expansion – clone that multiplies but does NOT change its binding specificity (antigen binding site can always bind to same antigen that initiated the activation) (IMPORTANT) |
front 18 2. Why must antibodies be made as membrane-bound BCRs before they are secreted? | back 18 They must be first bound as BCRs because when they interact with the antigen, the signal is sent to the B cell to proliferate and activate, THEN the BCR can be secreted (and now secreted is the antibody) its important that the interaction occurs while its bound on the membrane as a BCR so the cell recognizes the antigen to activate |
front 19 the pause for activity questions are sometimes used to make exam questions? | back 19 I think he said this |
front 20 BCR transmits intracellular signals via associated Igalpha and Igbeta proteins | back 20 B cell receptor = antibody = Ig BCR functions
BCR can directly bind to antigen particles, bacteria, viruses they are highly flexible in terms of what structure they can recognize
flexibility of binding and almost no limit as to what the BCR can bind
B cells see structures, while T cells see proteins, peptides, only amino acid sequence |
front 21 B cell and T cell antigen binding molecules | back 21 (PIC) BCR vs TCR - KNOW THESE IN PIC antigen recognition thru combination binding - heavy chain and light chain - together form the antibody molecule
many effector functions of antibody once secreted come from the constant region (base/bottom part)
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front 22 3. What are some similarities and some diffs btw BCR and TCR? | back 22 no data |
front 23 there is an antibody for every possible antigen | back 23 very important to know this! |
front 24 Each B cell clone produces a unique ability | back 24
When antigen come, will find one of the clones specific for that pathogen/antigen Ex: yellow recognize the pathogen, multiplies, and then produces the same antibody - secrete BCR in form of antibody – is the same antibody that each clone is making How is it possible that there are so many diff clones generated? Will probably address later on B cell clone - population of B cells which have the same BCR and bind to the same Ag |
front 25 clonal selection hypothesis | back 25 Undergo clonal expansion (only B cell receptor (BCR) undergoes this) -> multiply -> millions of the B cell clone 2000 molecules/second antibodies made They are everywhere – why they are effective Efficacy lies in mass number og molecules Key: antibogies = templates made pre-exposure to pathogen - clones are premade (existing ID for everyone card analogy) templates (Abs) pre formed against all antigens |
front 26 clonal selection upon antigen encounter | back 26 lymphocyte precursor -> mature -> clones of mature lymphocyte for many antigens einter lymphoid tissue -> antigen specific clones are activated my antigens -> antigen specific immune responses occur Specificity does not change by expansion of numbers B cell clone - population of B-cells which have the same BCR and bind to the same Ag |
front 27 4. A. Why are antigen-specific BCRs made before encountering the
antigens? | back 27 no data |
front 28 antigen specific B cell clone can be used to produce monoclonal antibody | back 28 antigen specific B cell clone can be used to produce monoclonal antibody
monoclonal - mono specificity Antibody can be a drug - first biological drugs invented - all biological processes need molecular interactions - antibodies bind specific structures, bind to them and can prevent interactions - if certain interaction causes disease, then the interaction is blocked and disease stopped Ex: cancer cell B cell – specific clone of the antibody lives forever, and makes the antibody you want - isolate spleenocytes from animal - mix them w/ cancer cells = some of the immune cells become immortalized = antigen specific B cell immortalized -> then continuously make antibodies. Have it proliferate and make many in vitro for drug/therapeutic/medicine purposes = power of clonal expansion Clonal expansion of B cells and T cells is extremely important + key for efficacy of adaptive immune system Have clonal expansion – have millions of cells -> some kept for memory, some become plasma cells and only make antibodies |
front 29 see take aways | back 29 no data |