Reference no: EM133240828
1. Summarize the similarities and differences between BCRs/antibodies and TCRs including structure, generation of diversity in antigen binding sites, generation of isotypes, mechanism of antigen recognition, subunits responsible for signal transduction, and function of co-receptors. Be sure to include Subunits responsible for signal transduction? Generation of isotypes? Co-receptors? Diagrams?
2. Demonstrate TCR and BCR complexes, showing how the receptors and the accessory proteins are arranged in the lymphocyte membrane, indicating the variable and constant regions and the antigen binding sites, and showing how the receptor subunits and signalling components are linked to each other. Include the B cell and T cell co-receptors in your drawings.
3. Two children in a family present with repeated viral infections that are difficult to resolve but so far have not been fatal. Flow cytometry shows very low levels of HLA class I proteins on leukocytes and reduced numbers of CD8+ lymphocytes, but normal levels of CD4+ lymphocytes and B cells, and increased numbers of activated NK cells.
What genetic defect might explain these results? Give your reasoning. Be sure to account for all of the observations. This question states that Class I MHCs are missing. What mutations might cause this? Why are there no CD8+ T cells and why increased levels of activated NK cells?
4. Human cytomegalovirus is a master at evading the immune system and can cause serious, often fatal infections in the immunocompromised. List 3 ways that CMV can evade being eliminated by cytotoxic T cells, and 2 ways it can evade NK cells.
5. Where are gamma:delta T cells generally found in the body and what kinds of antigens do they recognize? What do they do when they become activated?
6. More 90% of corneal transplants are successful, regardless of MHC matching or immunosuppressive drugs. Why aren't corneal transplants usually rejected?
7. Why are pigs considered to be good candidates as a source of organs for xenotransplantation? What are three barriers to xenotransplantation of pig organs?
8. Explain the advantage for an individual of being heterozygous for as many MHC alleles as possible and indicate what natural forces might favour the frequency of heterozygotes in a population.