Immunology: Cytokine Classification Quiz

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Questions and Answers

Which of the following cytokines is NOT classified as belonging to the Class 1 (hematopoietin) cytokine family?

IL-10 (correct)

G-CSF

IL-6

IL-4

What is a primary function of members of the interleukin-17 family?

Inducing apoptosis in tumor cells

Mediating antiviral responses

Promoting cytotoxic T-cell activity

Supporting neutrophil accumulation and activation (correct)

Which of the following statements about tumor necrosis factor (TNF) family members is correct?

They are always membrane-bound.

They share the same function as chemokines.

They are all soluble proteins.

They can be either soluble or membrane-bound. (correct)

Which of the following cytokines is classified under the Class 2 (interferon) cytokine family?

IFN-γ Signup and view all the answers

What role do chemokines typically play in the immune response?

Chemoattraction of immune cells Signup and view all the answers

What is the primary function of IL-1 in immune responses?

Promotes inflammation and recruits leukocytes Signup and view all the answers

Which cytokines are associated with the common gamma chain (γc) receptor?

IL-2, IL-4, IL-15 Signup and view all the answers

Which of the following statements about type I interferons is correct?

They induce synthesis of ribonucleases and inhibit protein synthesis Signup and view all the answers

What role does TNF-α play in the immune system?

It is proinflammatory and produced by activated macrophages Signup and view all the answers

What is the common receptor subunit for the cytokines IL-6, IL-11, and IL-27?

gp130 Signup and view all the answers

Which of the following cytokines is classified as a type II interferon?

IFN-γ Signup and view all the answers

How do Class I cytokines differ from others in terms of structure?

They generally consist of a single protein or multiple subunits Signup and view all the answers

Which of the following cytokines is primarily secreted by activated macrophages and dendritic cells?

TNF-α Signup and view all the answers

What is the primary role of C-type lectin receptors (CLR)?

Phagocytosis and inflammation Signup and view all the answers

What type of signaling action do cytokines exhibit when they affect nearby cells?

Paracrine action Signup and view all the answers

Which receptor type is primarily associated with detecting viral RNA?

Retinoic acid inducible gene-I-like receptor Signup and view all the answers

What is a primary effect of signaling through cytokine-receptor binding?

Change in cellular metabolic state Signup and view all the answers

Which of the following describes a pleiotropic effect of cytokines?

Induces different biological effects based on target cell Signup and view all the answers

What family of cytokines includes IL-1α and IL-1β?

Interleukin-1 family Signup and view all the answers

What mechanism describes the combined effect of two cytokines leading to a result greater than the sum of their individual effects?

Synergistic effect Signup and view all the answers

What is the function of the Absent-in-melanoma-like receptors?

Recognize viral and bacterial DNAs Signup and view all the answers

Which statement is true regarding cytokine signals?

Cytokine signals can instruct cells to change their state. Signup and view all the answers

Which type of action describes a cytokine that affects the cell that released it?

Autocrine action Signup and view all the answers

Which cytokine family is primarily involved in proinflammatory responses?

IL-17 family Signup and view all the answers

What is the primary function of BAFF and APRIL in the immune system?

Facilitating B-cell development Signup and view all the answers

What is the primary function of the cytokines produced by macrophages and neutrophils?

Pathogen destruction Signup and view all the answers

What type of receptors do chemokines interact with to facilitate leukocyte migration?

G-protein-coupled receptors Signup and view all the answers

What signaling event often results from the binding of a ligand to its receptor?

Transcriptional activation Signup and view all the answers

What do dendritic cells enhance in the immune response?

Antigen presentation Signup and view all the answers

Which receptor structure is characteristic of B-cells?

B-cell receptor similar to antibody Signup and view all the answers

Which of the following is regarded as an effector of programmed cell death in immune responses?

Fas Ligand Signup and view all the answers

Which accessory proteins are associated with B-cell receptors?

CD19, CD21, and CD81 Signup and view all the answers

What is a significant result of tyrosine phosphorylation of ITAMs?

Transmission of T-cell differentiation signals Signup and view all the answers

How do chemokines usually dictate their structural categories?

By the number of disulfide bonds Signup and view all the answers

What is a requirement for Naïve T-cells to become activated?

CD28 co-stimulation Signup and view all the answers

What type of ligands do T-cells primarily bind?

MHC class I and II molecules Signup and view all the answers

What general feature do all IL-17 family cytokines share?

They exist as dimers Signup and view all the answers

The cytoplasmic tails of which complex contain ITAMs for signal transduction in T-cells?

CD3 complex Signup and view all the answers

Which co-receptors are primarily associated with T-cells?

CD4 and CD8 Signup and view all the answers

What initiates the activation of Ras?

Exchange of GDP for GTP by GEFs Signup and view all the answers

Which step involves the breakdown of phosphatidyl inositol bisphosphate (PIP2)?

Step 03 Signup and view all the answers

What is the role of phosphokinase C (PKC) in the signaling pathway?

Phosphorylates IκB. Signup and view all the answers

What is the combination of phosphorylated Jun and phosphorylated Fos known as?

Transcription factor AP-1 Signup and view all the answers

Which of the following molecules is responsible for binding calcium ions?

Calmodulin Signup and view all the answers

What happens to IκB when it gets phosphorylated by PKC?

It is targeted for degradation. Signup and view all the answers

Which immune cells exhibit antigen peptides on MHC class I and class II?

Dendritic cells Signup and view all the answers

What is the primary effect of activated NF-κB in the nucleus?

Enhances transcription of immune-specific genes. Signup and view all the answers

Study Notes

Introduction to Sensations: Receptors and Signaling

The presentation discusses sensations, receptors, and signaling pathways.
It also details supporting literature, research, and specific questions for discussion.
The content covers various aspects of the immune response to internal and external cues.

Supporting Literature

Kuby Chapters (Chapter 3): This section refers to a textbook chapter.
AP-1, NF-kB, NFAT Pathways: These pathways are essential signaling pathways in cells.
Innate Lymphoid Cells: These cells play a crucial role in the innate immune system.
CXC44 and HIV: This refers to a protein and a virus.
HIV-membrane Fusion, CXCR4-HIV: These terms relate to how HIV enters cells.
TCR/TLR: These are receptors involved in immune responses.
Overview of TCR, TLR Minireview: A review on these T-cell receptors and Toll-like receptors.

Discussion Points

Cytoplasmic Signaling Molecules: What are the cytoplasmic signaling molecules and their function?
Principal Functions of TNF: What are the primary functions of Tumor Necrosis Factor (TNF)?
Transcription Factors in T-cell Activation: What are the three primary transcription factors involved in antigen-dependent T-cell activation, and how do they work?

Session 2

A quote by Anne Morrow Lindbergh emphasizes the importance of communication in her work.

Ligand-Receptor Interactions

Non-covalency: Cell-to-cell communication in immunology relies on non-covalent receptor-ligand interactions.
Affinity: The strength of individual noncovalent bonds tends to be weak.
Avidity: Multiple bonds creating a strong cumulative interaction.
Valency: Increasing the number of binding sites on receptors.

Univalent vs Bivalent Interactions

Univalent interactions involve a single binding site.
Bivalent interactions involve two or more binding sites, resulting in greater avidity.

Receptor Expression Changes

Space: Receptor expression can dynamically change its structure in response to external stimuli.
Time: Receptor expression can change over time during an infection process.

Receptor-Ligand Interactions

Conformational Change: When a ligand binds to a receptor, it induces a conformational change.
Dimerization/Clustering: Receptor binding often leads to dimerization or clustering.
Membrane Location Changes: The receptor's location within the membrane can change.
Covalent Modifications: Covalent modifications of the receptor can occur as a result of the ligand-receptor interaction.

Benefits of Receptor Multimerization

Cell-cell Interactions: Cell-cell interactions often rely on long-duration contacts with high-affinity binding.
Cytokine Signal Exchange: Extended contacts facilitate signal transduction, optimizing the exchange of cytokine signals.

Adaptive Immune Receptors

Immunoglobulin (Ig) Domains: Immune receptors possess immunoglobulin domains.
B-cell Receptor (BCR): The BCR binds foreign antigens. (Antibody).
T-cell Receptor (TCR): The TCR recognizes foreign or self-peptides presented on MHC molecules.
CD4/CD8 Co-receptors: These receptors help define T-cell subsets.

Co-receptors and Their Role

Enhanced Interactions: Antigen-immune receptor interactions are enhanced via co-receptor binding.
Separate Receptor Interactions: Co-receptors are separate receptor-ligand interactions.
Insufficient Single Interaction: A single receptor-ligand interaction often isn't sufficient, emphasizing the need for co-receptors.

Immunoglobulin Structure

Two Heavy Chains, Two Light Chains: Immunoglobulins are composed of two heavy chains and two light chains.
Covalent Disulfide Bonds: These chains are held together by intra- and interchain disulfide bonds.
Variable and Constant Regions: Heavy and light chains have variable regions and constant regions.

Antibody Structural Differences

Five Major Isotypes: Secreted antibodies are categorized into five major isotypes (classes).
Different Functions: Each isotype performs different functions within the immune response.
Kappa and Lambda Light Chains: Common light chain types are kappa (κ) and lambda (λ).

Immunoglobulin (BCR) Details

Antigen Binding Domains: Each antibody can bind two antigens.
Hinge Region: The hinge region extends the "arms" of the antibody.
Glycosylation: Glycosylation helps spread heavy-chain domains apart, playing a functional role.
Hydrophobic Tail: Membrane-bound antibodies often have a hydrophobic tail.
Alternative RNA Splicing: Secretion of antibodies is frequently processed via alternative RNA splicing.

T-cell Receptor (TCR) Details

Immunoglobulin Domains: Similar to BCRs, TCRs possess immunoglobulin domains.
Subunits alpha and beta: TCRs contain subunits alpha and beta.
CDRs (Complementarity Determining Regions): Three CDRs in the variable regions enable peptide-specific binding.
Transmembrane Regions: Constant regions contain transmembrane regions.
Types: Common are alpha-beta (αβ) and gamma-delta (γδ), exhibiting diverse antigen-binding characteristics.

Signal Transduction Pathways (TCR and BCR)

CD3 Complex and ITAMs: In T-cells, the CD3 complex is involved in signal transduction, relying on immunoreceptor tyrosine-based activation motifs (ITAMs).
Iga/Igb and ITAMs: In B-cells, Iga/Igb proteins initiate signal transduction through ITAMs.

Innate Immune Receptors

Pattern Recognition Receptors (PRRs): PAMPs (Pathogen-Associated Molecular Patterns) trigger PRRs, which broadly recognize many pathogens.
Uniform Recognition of PAMPs: The same PRR can recognize large numbers of pathogens that share the same PAMPs.
Equal Expression on Cells: PRRs are expressed equally across the same cell types, unlike unique receptors on adaptive immune cells.

Human PRRs (Toll-like, C-type lectin, RIG-I-like, NOD-like, AIM-like)

Cellular Locations and Ligands: These receptors differ in their location within the cell and the types of ligands they recognize.
Cellular Functions: These receptors perform various functions like producing antimicrobial compounds, cytokines, etc.

Cytokine Signaling Molecules

Cytokine Signals: These signals are generated when ligands bind to their complementary cell-bound receptors.
Generally High Affinity (Non-covalent): The binding is typically of high, non-covalent affinity.
Cytokine-receptor Signal Outcomes: These interactions result in changes to the target cell's transcriptional program (e.g., metabolic or proliferative changes).

Cytokine Action Mechanisms

Endocrine: Cytokines released into the bloodstream act on distant cells.
Paracrine: Cytokines act on nearby cells.
Autocrine: Cytokines act on the cell that produced them.

Cytokine Action Patterns

Pleiotropic: A single cytokine can have multiple effects.
Redundant: Multiple cytokines can produce similar effects.
Synergistic: The combination of cytokines can produce a greater effect.
Antagonistic: One cytokine can inhibit the effect of another.
Cascading: One cytokine can induce the production of additional cytokines.

Practical Examples of Cytokine Action

Immune Cell Activation, Proliferation and Differentiation: Activated T cells can stimulate the proliferation, differentiation, and activation of other immune cells in response to specific stimuli and signals.

The Six Cytokine Families (Interleukin, Interferon, Tumor Necrosis Factor, Interleukin-17, Chemokines)

Representative Members: Specific cytokines provide examples of each type of cytokine family.
Common Features: General features (e.g., functions or actions) of each cytokine family are listed.

IL-1 Family

Inflammation: This family of cytokines promotes inflammation.
Early Immune Response: Secreted early in immune responses, acted on by macrophages and dendritic cells.
Actions: Acts on capillary permeability and pulls leukocytes to infected sites.
Acute Phase Proteins: Systemic signalling promotes acute phase protein production.

Class 1 Cytokine Family

Diverse Function: Class 1 cytokines are diverse in actions and targets.
Single Protein Family: Structurally, class 1 cytokines are typically single proteins (but may have multiple subunits).
Common Subunits: Multiple cytokine types can use common cytokine receptor subunits, leading to functional similarities.

Interferon (IFN) Family

Antiviral Effects: Type I interferons have antiviral effects.
Immunomodulation: Type II (IFN-γ) interferons are important modulators of adaptive immunity.
Viral Replication Control: Type III interferons regulate genes controlling viral replication and host cell proliferation.

Tumor Necrosis Factor (TNF) Family

Development and Homeostasis: TNF affects development, effector function, and homeostasis in skeletal, neuronal, and immune systems.
Soluble / Membrane-Bound: TNF cytokines can be membrane-bound or soluble.

IL-17 Family

Proinflammatory: IL-17 family cytokines are proinflammatory.
Cellular Targets: Receptors are found on cells important for immune interactions (i.e., neutrophils).
Homodimers: The family members tend to exist as homodimers.

Chemokines

Leukocyte Migration: They are small proteins driving the migration of leukocytes.
Disulfide Bonds: Conserved disulfide bonds dictate the structure of each type.

Chemokine Receptors

G-protein-Coupled Receptors: These are transmembrane proteins coupled to G-proteins.
Signal Transduction: Signal transduction follows binding to their G-proteins.
Chemokine Recognition: One receptor can sometimes bind more than one chemokine. Conversely, more than one chemokine can sometimes bind the same receptor.

Cellular Signaling Summary

Ligand-Receptor Binding: Cellular signals are frequently triggered by ligand binding to receptor proteins.
Programmed Changes: Signaling mechanisms frequently induce changes (in the cell's metabolic or proliferative state).
Ligand Expression: A cell's responsiveness to a signal can change through regulation of receptor expression for that ligand.

Multiple Signals and Cellular Response

Transcription Program Changes: Cell signaling frequently results in changes to the cell's transcriptional program.
Integration and Outcomes: Various signaling pathways, potentially involving multiple receptors, frequently work together (integrate) to produce overall outcomes within a recipient cell.

Summary of Immune Responses and Signaling

The steps of immune cell involvement in antigen response.
The critical role of immune cells in antigen presentation.

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Description

Test your knowledge on the classification and functions of various cytokines in the immune system. This quiz covers topics including Class 1 (hematopoietin) and Class 2 (interferon) cytokines, their functions, and key receptors. Challenge yourself with questions about IL-1, TNF-α, and more.