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WVSOM immuno lec 7
WVSOM immunogenetics lec 7 immuno
| Question | Answer |
|---|---|
| Things to happen before an infection can occur? | infectious organism has to overcome the host defenses |
| What is the response of an inoculation of an antigen? | the host initiates an inflammatory response, and innate defense mechanisms, in the mean time the antigens are being presented to the lymphoid organisms, lymphocytes are being activated, lymphocytes come out and secrete antibody |
| If there were one gene for each protein that was recognized by the immune system how much of the genome would it take up? | almost the entire genome |
| So b cells the receptors on their surface are what? | antibody |
| The specificity takes place in which region of the antibody? | the antigen binding site that is made of the variable light and variable heavy chains of the antibody |
| Remember what an antibody looks like state how many heavy or light chains as well as any constant or variable regions? | two light chains with a constant region and a variable region, two heavy chains with a variable region and at least 3 constant regions |
| The variable region its self is encoded by how many different gene segments? | two or more different gene segments for the light its 2 for the heavy 3 different gene segments |
| Why is the V segments bigger? | because they encode the most part of the amino acids |
| Lets look at a kappa light chain how is it encoded? | the variable part of the light chain about 100 amino acids is encoded by two different gene segments of which the cell has several to chose from, ~40 V segments and ~5 J segments |
| Two names that you have to remember RAG1 and RAG 2 they stand for recombinase activating gene what do they do? | they help the process of recombination |
| Severe Combined Immuno Diffeciency (SCIDs) where the patients immune system is severely compromised one form is caused by a defect in what? | RAG genes where the B cells and T cells are unable to form receptors so you are unable to form an immune system |
| The entire binding site is composed of what? | the variable region of the light chain and the variable region of the heavy chain |
| Now lets look at the heavy chain, the variable region is encoded by 3 different gene segments what are these segments? | V (~40), J (5 or 6), D (~20) segments so again the possibilities are huge |
| Are the antibody in different order and what cells undergo combinations to form antibody? | They are always in this order, only the B cells are going to undergo this combination to form antibody |
| Which immunoglobulin segment will be encoded first on the heavy chain? | the closest to the variable region (IgM) and (IgD) |
| Are the specificities of the IgM and IgD from the same immunoglobulin encoding regions different? | no they have the same specificity |
| In an acute organism infection which antibody will be most prevalent in the immune response? | IgM |
| If you have a second exposure to an organism what is the most prevalent antibody in the immune response? | IgG |
| How is antibody diversity created? | clones with unique receptors, gene segments encode receptor proteins, random combination of segments |
| How is antibody diversity created? | clones with unique receptors,gene segments encode receptor proteins, random combination of segments, differences in joining points of segments, terminal deoxynucleotidyl transferase (TdT), light chain plus heavy chain combinations, somatic hypermutations |
| What is the role of TdT? | at the same time expressed in the developing cells adding more and more nucleotides so they encode different proteins in the different segments so now we have an explosion of different receptors |
| What is the role of Somatic hypermutations? | b cells when they proliferate the genes for immunoglobulin receptors undergo hypermutations even if cells have the same gene segments to encode antibody receptors the clones may not have exactly the same receptor because of these mutations that occur |
| Trace out the life of a B cell? | starts in bone marrow, stem cell to lymphoid progenitor to pro-B cell to Pre-B cell to immature B-cell then goes to periphery, Mature B cell which goes to either a plasma cell or memory B cell that can go to plasma cells |
| Cells are forming receptors all the time those that are self reactive what happens to those? | get eliminated |
| Mature b cells hang out in the secondary lymphoid organs where if they come in contact with antigen what happens? | become plasma cells or memory cells |
| How does binding to the antibody receptor signal the nucleus to begin dividing if it has very little cytoplasmic connection? | there are other cells that are in association with the receptor that have a cytoplasmic component, it undergoes conformational changes and phosphorilations happen, this is very important for signal transduction |
| Remember RAG 1 and RAG 2 these are the recombinase genes that facilitate that segment rearrangement when will they be expressed? | they will be expressed early as the cell is rearranging but not in the mature cell |
| The role of TdT again will be? | adding random nucleotides to those gene segments that are being recombined |
| What is Isotype switching? | b cell becomes active proliferates now some of the clones will switch to another type IgM IgA ect |
| How does the cell undergo isotype switching? | The cell will splice out a portion bringing closer to another segment that will encode for a different immunoglobulin IgG for example |
| People with allergies tend to have more of the T cells that express IL4 and you get more what antibody? | IgE antibody |
| Which has better affinity for antigen, IgM or IgG? | IgG |
| If over time you are still exposed to an antigen what is the response you get with the antibodies? | first you get a response with IgM but as the exposure prolongs you get a switch to IgG which gets better and the affinity for the antigen increases as well |
| What may happen is that you may have a translocation of an oncogene what is this? | you have a transfer between chromosomes that usually leads to cancer |
| Why do you get cancer when you have a translocation between chromosomes? | because the normal regulation has been removed from that segment that has been transferred and could cause an anomaly such as cancer |
| What is Burkitt’s lymphoma? | a cancer causing a swollen tummer in the jaw, caused by a chromosomal anomaly where you have a translocation between chromosome 8 and 14 that can be caused by a strain of the herpes virus |
| When does a baby start to make its own antibody? | A baby starts to produce its own antibody about 30 to 32 antibody, mostly IgM some IgA |
| What is the make up of a babies immune system when born? | Most of the IgG in the circulation of the baby comes from the mother |
| When is the baby is making a lot of IgM and IgG some IgA is coming into play but not much? | By one year of age |
| Which antibody is allowed to cross the placenta into fetal circulation? | IgG |
Created by:
hagerman
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