Cytokines and Chemokines Overview

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Questions and Answers

What is meant by pleiotropic action of cytokines?

Different target cells respond differently to the same cytokine. (correct)

A single cytokine exerts the same effect on all target cells.

Two cytokines combining their effects yield an additive result.

One cytokine inhibits the activity of another cytokine.

Which of the following best describes redundant action of cytokines?

A cytokine inhibits another cytokine's effects.

One cytokine's effect boosts the functions of another.

Multiple cytokines exert the same effect on the same cells. (correct)

Cytokines act only in the area immediately surrounding their source.

What does synergistic action of cytokines involve?

The combined effect of two cytokines is greater than their individual effects. (correct)

One cytokine's activity nullifies another's effect.

One cytokine acts on a distant cell.

Cytokines only function in the context of inflammation.

Antagonistic action of cytokines can be best described as which of the following?

A cytokine suppressing the effect of another cytokine. Signup and view all the answers

Which of the following is NOT a biological function of cytokines?

Induction of hormonal responses. Signup and view all the answers

Which property allows cytokines to regulate immunocompetent cells in a coordinated manner?

Their pleiotropic and redundant actions. Signup and view all the answers

What distinguishes the effects of cytokines from those of hormones?

Cytokines can have short-lived secretions compared to hormones. Signup and view all the answers

What role do chemokines play in the immune response?

They facilitate the migration and activation of leukocytes. Signup and view all the answers

Which statement accurately reflects the action of cytokines?

Cytokines can bind to any cell with a corresponding receptor. Signup and view all the answers

What does the term 'pleiotropic action' refer to in the context of cytokines?

Cytokines having the ability to produce multiple effects on different target cells. Signup and view all the answers

Redundant action in cytokines signifies that:

Different cytokines can trigger similar biological responses. Signup and view all the answers

Which of the following describes synergistic action among cytokines?

Two or more cytokines enhancing each other's effects. Signup and view all the answers

Antagonistic action of cytokines involves:

One cytokine inhibiting the effect of another. Signup and view all the answers

What is NOT a biological function of cytokines?

Causing physical damage to tissues. Signup and view all the answers

Which statement about interleukins (IL) is correct?

There are currently around 40 known interleukins. Signup and view all the answers

The binding of cytokines to their receptors primarily results in:

Activation or suppression of signal transduction pathways in target cells. Signup and view all the answers

What characteristic of cytokine receptors enhances their function?

High affinity for their cytokine ligands. Signup and view all the answers

Which mechanism of action involves cytokines moving immune cells towards areas of higher concentration of cytokines?

Chemotaxis. Signup and view all the answers

What term describes the phenomenon where cytokines promote different but complementary responses in the immune system?

Synergy. Signup and view all the answers

Study Notes

Cytokines

Low molecular weight proteins or glycoproteins produced by lymphocytes and other cells
Originally called lymphokines or monokines
Many are called interleukins (IL) because they are produced by leukocytes and act on leukocytes
There are over 40 known ILs
Play a crucial role in coordinating interactions between cells in the immune system
Have various actions: autocrine, paracrine, endocrine
Action is pleiotropic, redundant, synergistic, antagonistic, and cascade
Act in an antigen-nonspecific manner, binding to any cell expressing the appropriate receptor

Chemokines

Another group of molecules important in leukocyte communication
Recruit and activate leukocytes, playing a key role in chemotaxis (movement of cells toward higher concentrations of signaling molecules)
Function in various physiological processes: inflammation, wound healing, angiogenesis, development of brain and heart tissue
Induction of chemokine secretion: microbes or cytokines (TNF-α)
Chemokines trigger the expression of chemokine receptors and adhesion molecules on leukocytes and endothelium, leading to leukocyte adherence to endothelium and diapedesis (migration through blood vessel walls)

Cytokine Receptors

Cytokines exert their effects by binding to specific receptors on target cells
Belong to four protein families: Class I cytokine receptors, Class II cytokine receptors, TNF receptor superfamily, and Chemokine receptors
Most receptors are composed of multiple subunits, with at least one required for cytokine binding and another for signal transduction

IL-2 Receptor

Composed of three chains: α, β, and γ
Exists in three forms with different affinities for IL-2:
- Monomeric IL-2Rα: Low affinity
- Dimeric IL-2Rβγ: Intermediate affinity
- Trimeric IL-2Rαβγ: High affinity

Chemokines: Classification and Receptors

Superfamily of small polypeptides (90-130 amino acids)
Classified based on the location of the first two conserved cysteins:
- C chemokines: The first two cysteins are bound by side disulphide bonds.
- CC chemokines: The first two cysteins are positioned one after another, each with a side chain.
- CXC chemokines: An amino acid (X) other than cysteine is located between the first two conserved cysteins.
- CX3C chemokines: Three amino acids other than cysteine are located between the first two conserved cysteins, and there is a mucin domain.
Act through their receptors, which have a similar structure:
- Extracellular domain for chemokine binding
- Seven transmembrane domains
- Intracellular domains α, β, and γ, associated with the G-protein (G-coupled proteins)
Receptor names reflect the type of chemokine they bind to:
- CR: C chemokines
- CCR: CC chemokines
- CXCR: CXC chemokines
- CX3CR: CX3C chemokines

Pro-inflammatory Chemokine Panel

This panel consists of several chemokines involved in inflammatory responses:
- CCL2 (MCP-1)
- CCL4 (MIP-1β)
- CCL5 (RANTES)
- CXCL9 (MIG)
- CXCL10 (IP-10)
- CCL20 (MIP-3α)
- CXCL5 (ENA-78)
- CCL11 (Eotaxin)
- CXCL1 (GROα)
- CCL17 (TARC)
- CXCL11 (I-TAC)
- CCL3 (MIP-1α)
- CXCL8 (IL-8)

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Description

Dive into the world of cytokines and chemokines, crucial proteins in the immune system. Learn about their roles, functions, and various types such as interleukins. This quiz covers essential aspects of these signaling molecules and their significance in cell communication and immune response.