Exam 2 (Lecture 14) - Response To Different Types of Pathogens and Tolerance Flashcards
Label a diagram of the interaction between an antigen-presenting cell and a T and B cell in a primary or secondary response for parasites and viruses; and primary response for extracellular and intravesicular bacteria. (Blank or darkened out diagrams are on Canvas for practicing).
Done.
Describe the difference between how central and peripheral tolerance is induced.
Central:
- Lymphocytes are getting BCRs and TCRs; if they bind to self-antigens, they get deleted
Peripheral:
- The mature naive lymphocytes may bind to any antigen without co-stimulatory molecules/danger signals if so, will be deleted
Explain the major components of T cell tolerance - when, where, and how it develops:
a. Development of important surface molecules
b. Positive selection
c. Negative selection
d. Role of thymic epithelial cells and APCs in the thymus
Development of surface receptors:
- When: they first enter the thymus as a T cell
precursor (thymocyte)
- Where: cortex of thymus
- How: proliferates, begin to mature, and develop
TCR, CD4+, and CD8+ (TCRs are randomly
generated)
Positive Selection
- When: after TCRs are generated
- Where: cortex of the thymus
- How: has to bind to MHC I or MHC II (if recognize
= live; if not = die); loses other CD not required
for that MHC (ex: if binds MHC II then keeps
CD4+ but loses CD8+)
Negative Selection:
- When: after TCRs are generated
- Where: medulla or cortex of thymus
- How: if recognizes peptide (self) in MHC groove
= die; if not = live)
Role of Thymic Epithelial Cells and APCs:
- When : during positive and negative selction
- Where: cortex of thymus
- How: thymic epithelium ensures self-reactive T
cells are negatively selected (eliminated) and
APCs allow them to express and present many
proteins normally found in nonthymic tissue
Describe how the thymus changes with age and how that relates to immunity and disease later.
Thymus regresses with age.
Thymus dependent immunity decreases (cell-mediated immunity) and this leads to increases in diseases like cancer, autoimmune disease, and various infectious diseases.
An animal is exposed to roundworms and mounts a primary immune response. Label the cells and molecules of the simplified diagram explaining the primary response to the roundworms. (Key is posted).
Done/printed
An animal is exposed to and infected with Mycobacterium bovis (bovine TB), an intravesicular pathogen. It mounts a primary immune response. Label the cells and molecules of the simplified diagram explaining the primary response to this pathogen. (Key is posted)
Done/printed
An animal that was previously vaccinated for influenza is exposed to influenza but doesn’t have detectable clinical signs. Serologic samples indicate that there was exposure and an immune response, i.e. thee IgG titer was elevated. Label the cells and molecules of a simplified diagram explaining how the virally infected cells were detected and eliminated in this secondary process.
Done/printed
