Immuno Final Flashcards
(29 cards)
What is the function of Th17 cells in the immune defense?
Th17 cells produce IL-17 to recruit neutrophils for the destruction of fungi and some bacteria. Th17 releases IL-17, IL-21 (for GF of Th17), IL-23 (for B cell class switching to IgA and IgG3).
without IL-17 = devasting fungi infection
What is the significance of regulatory T cells (Tregs) in immune homeostasis?
Tregs suppress unwanted immune responses and maintain tolerance to self-antigens.
-Subset of CD4s
-Intermediate binding during self-recongition phase.
-Happens in Thymus
-Foxp3 expression for transcription factor (peripherals)
Natural: Inhibit naive T cell activation
Inducable Treg: inhibit APC to bind to T cells for activation and reduces hypersresonse to invaders
How is tolerance established during T and B cell development?
Through positive selection for functional receptors and negative selection against self-reactivity.
What is the significance of CD28 and CTLA-4 in T cell signaling?
CD28 provides necessary co-stimulatory signals for activation, while CTLA-4 inhibits T cell activation by outcompeting CD28 for B7.
How do IgE antibodies mediate hypersensitivity reactions?
IgE binds to allergens and activates mast cells and basophils, leading to the release of mediators during an allergic response.
Type 1 with basophil, mast cells and eosinophils. IgE will bind to FceRI on mast cells and basophils, if enough binds it will activate the cells.
What role do APCs play in the activation of naive T and B cells?
APCs present antigens and provide co-stimulatory signals necessary to activate naive T and B cells.
How do MHC I and MHC II differ in terms of structure and function?
MHC I presents to CD8+ T cells (cytotoxic), while MHC II presents to CD4+ T cells (helper).
What happens to T cells during activation-induced cell death (AICD)?
AICD eliminates T cells that have been repeatedly activated, making space for new naive T cells.
Fas-FasL -> suicide or homicide (NTK)
What mechanisms do T cells employ to avoid attacking self-antigens?
T cells undergo negative selection and require additional co-stimulation to become activated against pathogens.
What is the significance of co-receptors in T cell activation?
Co-receptors like CD4 and CD8 determine the type of T cell and help in recognizing peptide-MHC complexes.
What is the role of Th cells in orchestrating the immune response?
Th cells orchestrate the immune response by releasing cytokines that activate and direct other immune cells.
- Activate B cells to prodice Ab and Plasma cells
- Growth factor release
- Cyokines to recuit other immune cells
What is the role of CD40 and CD40L in B cell activation?
CD40 on B cells interacts with CD40L on T helper cells, facilitating B cell activation and antibody production.
How does molecular mimicry contribute to autoimmune diseases?
TCR/BCR may recognize pathogens but also cross-react with self-antigens, leading to autoimmunity. Since immune system may still be active, it will attack self angtigens that look like the pathogen that is dead.
Why is a co-stimulatory signal required in T cell-dependent activation?
To ensure both the B cell and T cell recognize danger and agree on the need for an immune response.
What are the main types of T cell memory and where do they reside?
Tissue-resident memory T cells remain in tissues, effector memory T cells circulate, and central memory T cells reside in secondary lymphoid organs.
What are the three types of antigen presenting cells (APCs)?
Activated dendritic cells, activated macrophages, and activated B cells.
What are the two ways a naive B cell can be activated?
T cell-dependent activation and T cell-independent activation.
How does PD-1 contribute to T cell lethargy in inflamed tissues?
PD-1 binding to PD-L1 in inflamed tissues results in reduced T cell activity and promotes exhaustion.
What is the difference between T cell-dependent and T cell-independent activation?
T cell-dependent activation requires help from T cells and co-stimulatory signals, while T cell-independent activation can occur without T cell involvement.
How do Th2 helper T cells contribute to the immune response against parasites?
They release IL-4, IL-5, and IL-13 to stimulate class switching in B cells to IgE for parasite defense.
What is the role of CD4 and CD8 co-receptors in T cell function?
CD4 is involved in helper T cell function (MHC II), while CD8 is involved in CTL function (MHC I).
How do B cells undergo somatic hypermutation during maturation?
B cells mutate their antibody genes to increase affinity for antigens, allowing for improved immune responses.
What is the process of receptor editing in B cells?
B cells with self-reactive BCRs can rearrange their light chain genes to avoid self-binding.
How do encapsulated organisms affect B cell activation in the spleen?
Spleen can activate B cells independently of T cells via marginal zone B cells in response to polysaccharide antigens.
