Week 9 Flashcards
(100 cards)
For innate immunity,
- Define innate immunity.
- What types of cells are involved?
- What immunue mediators are involved?
- Innate immunity
- First responder to infection, tissue damage, and inflammation
- Cells involved: include neutrophils, dendritic cells, macrophages, natural killer cells
- Immune mediators involved: interferons, cytokines, and chemokines
For adaptive immunity,
- Define adaptive immunity.
- What does it require?
- What cells are involved?
- What are the two types?
- Highly specific recognition of antigens
- Requires clonal expansion of memory cells
- Self-reactivity leading to autoimmune disease
- Cells involved: B-cells, T-cells, dendritic cells, and macrophages
- Types
- Humoral
- Cell-Mediated
What are the cells and their functions in:
- humoral immunity
- cell-mediated immunity
- Humoral
- B cells – creates antibodies (memory cell)
- Block infections and eliminate extracellular microbes
- Cell-mediated
- Cytotoxic T-cells – kills infected cells and eliminate reservoirs of infection (memory cell)
- Helper T-cells – eliminates phagocytosed microbes (memory cell)
What are the three major cell types?
- Lymphocytes
- Antigen-presenting cells
- Effector Cells
What two types of cells are called lymphocytes and how do they progress through their life cycle?
- Lymphocytes
- B-cells: humoral immunity
- T-cells: cell-mediated immunity
- Life Cycle: naïve cell → effector lymphocyte → memory lymphocyte
What cells types are in the subtype: antigen-presenting cells?
- What is the function of each cell type?
- Dendritic cells: initiation of T-cell response
- Macrophages: effector phase of cell-mediated immunity
- Follicular dendritic cells: initiation of B-cell response
What cells types are in the subtype: effector cells?
- What is the function of each cell type?
- T-cells: activation of phagocytes and killing of infected cells
- Macrophages: phagocytosis and killing of microbes
- Granulocytes: kills microbes
What are the four postulates in “The Clonal Selection Hypothesis”?
- Clonal Selection Hypothesis
- Each lymphocyte bears a single type of receptor with a unique specificity (by V(D)J recombination)
- Virus must bind to lymphocyte receptor for lymphocyte activation (selection)
- Daughter lymphocyte cells derived from an activated lymphocyte will bear receptors of identical specificity as the parental cell (clonal)
- Lymphocytes bearing receptors for endogenous molecules will be deleted at an early stage
Differentiate between primary and secondary immune responses.
- In primary immune response, response is slow because naïve B-cells must undergo V(D)J recombination in order to respond to first contact with an antigen → creates memory B-cells
- In secondary immune response, memory B-cells can respond quicker because of acquired specificity to antigen
Where do B-Cells and T-Cells mature?
- B-cells maturate in bone marrow
- T-cells maturate in thymus
What are some secondary homes for B-Cells and T-Cells?
- Within these tissues, where are B-cells and T-cells located?
- Secondary homes: B-cells peripherally, T-cells centrally
- Spleen
- Lymph nodes
- GALTs – gut-associated lymphoid tissues
- MALTs – mucosal-associated lymphoid tissues
What are the five phases of immune response in situ?
- “First responders” = innate immune cells
- Antigen presentation to naïve adaptive immune cells
- Clonal expansion; amplification of antibody and cytokines
- Pathogen elimination; contraction phase of the immune response
- Memory
What kind of cells can act as antigen presenting cells (APCs)?
- Antigens are captured by dendritic cells, macrophages, and B-Cells (pAPCs) in the epithelium
What is the process of antigen presentation leading to T-Cell
- Antigens are captured in the epithelium.
- Blood borne antigens are captured in the spleen
- Tissue resident APCs migrate to lymph nodes
- T-Cell activation
For Cytotoxic T-Cells, what is:
- the surface marker?
- the function?
- location of antigen source within a cell?
- MHC Class recognized?
- Surface Marker: CD8
- Function: Cell Killing
- Antigen Source: Cytosolic
- MHC Recognized: MHC Class I
For Helper T-Cells, what is:
- the surface marker?
- the function?
- location of antigen source within a cell?
- MHC Class recognized?
- Surface Marker: CD4
- Function: Promote macrophage activity and B-Cell function
- Antigen Source: endosomal
- MHC Recognized: MHC Class II
What is the structure of MHC Class I?
- How many alpha and beta chains?
- Expressed on what ells?
- Binds peptides of what size?
- MHC Class I
- 3 alpha chains and 1 beta chain
- Expressed on all somatic cells
- Binds short peptides (8 to 11 AAs)
What is the structure of MHC Class II?
- How many alpha and beta chains?
- Expressed on what ells?
- Binds peptides of what size?
- 2 alpha chains and 2 beta chains
- Expressed only on professional APCs (dendritic, B, and macrophage)
- Binds long peptides (11 to 30 AAs)
What facilitates the MHC binding proteins to bind peptides?
- How MHC Proteins bind peptides
- Binding site of MHC molecule only requires 2 to 3 AAs (anchor peptides)
- MHC molecules can bind large repertoire of peptides
What are the three important characterisitics of MHC proteins?
- MHC genes are polygenic (multiple genes code for single phenotype)
- MHC genes are polymorphic (high number of mutations)
- MHC gene expression is codominant (mom and dad alleles of MHC class proteins are equally expressed → 6 class I molecules can be expressed)
What are the three functions of the polymorphic nature of MHC genes?
- MHC genes are polymorphic (high number of mutations)
- Allows for diversity of peptides to bind
- Alters contact with T Cell Receptor
- Each T Cell Receptor can only recognize a single peptide/MHC combo
What are the three functions of the invariant chain?
- Binds newly formed MHCII in ER
- Blocks peptide binding groove
- Targets complex to endosome (Ii is degraded in endosome → CLIP (peptide of invariant chain) is unloaded from MHCII by HLA-DM)
In which pathway can cross presentation occur (MHC I or MHC II)?
- Professional APCs can activate both MHC I and II presenting pathways without being infected
- Normally, MHC I pathway happens in infected cells
What causes Type I Bare Lymphocyte Syndrome?
- Type I – loss of MHC class I expression
- Mutations in TAP





