Across
- 2. (2 word) The process of tolerance of self is also known as ______ ______, where T cells must NOT recognize the MHC-self peptide complexes presented on cells in the thymic medulla. This process eliminates self-reactive T cells.
- 3. (hyphenated) When bound to its ligand PD-1L, this protein inhibits the proliferation of previously activated T cells.
- 4. (1 word) The inner part of the thymus.
- 9. (2 words) _______ _______ epithelial cells are one of two cells involved in testing for tolerance of self. These cells use autophagy to present self antigens on MHC II molecules.
- 10. (hyphenated) A protein expressed on T cells that suppresses T cell activation because it has such a high affinity for the B7 protein on professional APCs. This makes B7 less likely to bind CD28 on T cells (which leads to T cell activation).
- 15. (2 word) The process of MHC restriction is also known as ______ ______, where T cells must have receptors that recognize one of the MHC-self peptide complexes on a cortical thymic epithelial cell to pass the “test.” This process eliminates T cells that recognize unpresented antigen.
- 17. (2 words) The process by which B cell receptors are tested to see if they recognize self antigens in the bone marrow.
- 18. (1 word) This abnormal method of self antigen presentation occurs when a cell digests its own innards and presents those self-peptides on class II MHC molecules.
- 19. (1 word) AICD works because a T cell becomes increasingly sensitive to ____ ligation the more times it is re-activated. This allows for most T cells to die after they’ve responded to a pathogen so we don’t have trillions of obsolete T cells in our bodies.
- 21. (1 word) Together, CTLA-4 and PD-1 function as ________ proteins, which help “decommission” T cells as the battle winds down.
- 23. (2 words) T cells that express both CD4 and CD8 co-receptors as they are being “educated” on tolerance of self are said to be _______-________ cells.
Down
- 1. (3 words) In this process, in case some naive T cells stray outside their prescribed traffic pattern and venture into the tissues, the peripheral tissues (ex. heart, kidney cells) will not express the co-stimulatory molecules necessary to activate the T cell.
- 4. (3 words) The process by which natural killer cells destroy our cells not displaying class I MHC molecules.
- 5. (2 words) B cells are tolerized in the ______ _______.
- 6. (2 words) _______ ______ cells are one of two cells implicated in testing for tolerance of self. Some of these cells can travel to the thymus from other parts of the body where they capture self antigens for presentation.
- 7. (4 words) The longevity of T cells can be a potential problem, and the solution to this is _______-________ _______ _______, which eliminates obsolete T cells after they’ve been re-stimulated many times.
- 8. (1 word) A type of regulatory T cell that helps to attenuate the immune response by protecting against self-reactive T cells.
- 11. (1 word) One of the ways to cease unneeded immune response is to ensure that many immune cells are ______-lived. ex. Neutrophils are programmed to die after a few days; plasma B cells die after about 5 days, etc.
- 12. (2 words) T cells that express only one of the co-receptor molecules (CD4 or CD8) are said to be ______-_______.
- 13. (3 words) The process of how T cells are first “educated” on tolerance of self, and it occurs in the thymus.
- 14. (1 word) The outer part of the thymus.
- 16. (1 word) Tolerance by ________ is the process by which TCRs with a low affinity, or self antigens that are rare, are so unlikely to ever encounter their respective self antigens or TCRs that the TCRs remain functionally “ignorant” of their presence.
- 20. (1 word) A type of regulatory T cell that helps to attenuate the immune response by preventing overreaction to foreign invaders, such as allergens.
- 22. (1 word) This occurs when a naive T cell can recognize its cognate antigen but does not receive the required co-stimulation from neighboring tissues. The T cell is said to be “neutered.”