Chapter 6 Definitions and Learning Objectives Define the following terms:Affinity MHC TCR Peptide On-off rate Antigen presenting cell (APC) Professional APC Immunogenic MHC restriction Costimulatory molecules Cell-mediated immunity Humoral immunity Langerhans cell MHC loci HLA Colocalization Cross-presentation Antigen processing Antigen presentation Proteasome TAP Invariant chain HLA-DM Tapasin CLIP Ubiquitin ERAP Phagolysosome Endolysosome Immunodominant Epitope Polymorphic Learning Objectives - Important concepts to know At the end of this chapter, you should be able to: 1. Explain how the characteristics of antigen receptors on T cells differ from those found on B cells. Your answer should (at least) include: a. the three different antigen receptors b. the cells each of the antigen receptors are found on c. the type of antigen each antigen receptor can bind d. the type of antigen each cell can recognize and be activated by e. the number of antigens the antigen receptors can bind f. the on-off rate of each antigen receptor g. the relative strength of antigen binding 2. Describe the various features of antigens that are recognized by T cells.4. Explain the two-signal hypothesis: a. what is the purpose of the two-signal hypothesis? b. what are the two signals (in general)? c. at what time do cells require two signals and others only require one? d. what are the results of the two-signal hypothesis? 5. Identify the various APCs (both professional and non-professional) and describe how they interact with T cells. Which T cells are involved? What is the result of each of these interactions? 6. Identify the best immune cell to activate naive T cells. Why is this the case? 7. Compare and contrast classical dendritic cells and plasmacytoid dendritic cells. 8. Compare and contrast antigen capture dendritic cells (also called tissue resident dendritic cells or immature dendritic cells) with activated dendritic cells (also called mature dendritic cells), including, at least, their: a. function b. location c. molecules/receptors expressed on the cell surface (explain the rationale of why certain molecules/receptors would be found on the cell surface at various time point during migration) 9. Explain the concept of MHC restriction and the experiment that proved this concept. 10. Explain the concept of codominant expression (of MHC genes). 11. Compare and contrast MHC I molecules and MHC II molecules, including: a. the structural components of MHC I molecules and MHC II molecules b. the genes that encode an MHC I molecule versus an MHC II molecule (also understand the rules of pairing) c. the cells in which each of the MHC molecules are expressed on d. how and where antigens are processed for each MHC pathway, including important molecules that assist in processing the antigen and stabilizing the MHC molecules e. the location in which MHC molecules are loaded with antigenf. the type of antigen MHC molecules can process and present (hint: extra- or intracellular) g. the type of T cell they can present antigen to (and subsequently activate) h. other important molecules involved in the MHC pathways i. rationalize the consequences of a defect at any stage in the MHC pathway 12. Describe cross-presentation and its advantages. What cell(s) can perform cross-presentation? 13. Describe how effector T cells identify antigen and perform their effector functions. (What are the different effector T cells?) 14. Describe the concept of immunodominance and its importance in antigen presentation and T cell activation. Question: Since MHC I and MHC II molecules are made at the same time, how do we make sure the “correct” peptide gets loaded onto the correct MHC
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