Immune Responses and Soluble Molecules

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Questions and Answers

What role do antimicrobial peptides play in the immune response?

They function only in the adaptive immune response.

They directly attack microbes or impede their reproduction. (correct)

They enhance the reproduction of pathogens.

They act as receptors that recognize pathogens.

Which of the following are types of pattern-recognition receptors (PRRs)?

Cytokine receptors and antibody receptors

Toll-like receptors (TLRs) and C-type lectin receptors (CLRs) (correct)

Complement receptors and membrane-bound receptors

Neutrophil receptors and macrophage receptors

What distinguishes pathogen-associated molecular patterns (PAMPs) from damage-associated molecular patterns (DAMPs)?

PAMPs are associated with microbial pathogens, while DAMPs are associated with host cell damage. (correct)

PAMPs are exclusively recognized by adaptive immunity.

DAMPs are utilized only in the presence of specific pathogens.

PAMPs are produced by host cells while DAMPs are not.

Which cells primarily express pattern-recognition receptors (PRRs)?

Neutrophils and epithelial cells Signup and view all the answers

Which type of immune response do complements participate in?

Both innate and adaptive immune responses Signup and view all the answers

How do defensins, a type of antimicrobial peptide, function?

By disrupting microbial membranes and inhibiting nucleic acid synthesis Signup and view all the answers

Why are pattern-recognition receptors also called primitive pattern recognition receptors?

They evolved before other parts of the immune system. Signup and view all the answers

What is one of the functions of cytokines in the immune response?

They facilitate communication between immune cells. Signup and view all the answers

Which of the following is a function of pattern recognition receptors (PRRs)?

Opsonization Signup and view all the answers

What type of receptors are Toll-like receptors (TLRs) primarily considered?

Membrane-spanning receptors Signup and view all the answers

What do nucleotide-binding oligomerization domain-like receptors (NLRs) primarily recognize?

PAMPs and DAMPs Signup and view all the answers

What structures do TLRs possess that are important for their function?

TIR domain and leucine-rich repeats Signup and view all the answers

Which of the following receptors recognizes carbohydrate components?

C-Type Lectin Receptors (CLRs) Signup and view all the answers

How many distinct TLRs are present in humans?

12 Signup and view all the answers

What is a characteristic feature of C-Type Lectin Receptors (CLRs)?

They recognize sugar moieties and have signaling functions. Signup and view all the answers

What structural feature do NLRs possess related to their functionality?

Three-domain structure including LRR and EBD Signup and view all the answers

Study Notes

Immune Responses and Soluble Molecules

Soluble molecules play critical roles in both innate and adaptive immune responses.

Innate Immune Responses

Cytokines: Include interleukins (IL) and interferons (IFN), signaling proteins that mediate immune responses.
Antimicrobial Peptides:
- Target and eliminate microbes or inhibit their reproduction.
- Defensins are key examples, categorized into α-defensins and β-defensins, known for disrupting microbial membranes and inhibiting RNA, DNA, and protein synthesis.
- Primarily produced by neutrophils and epithelial cells.
Complement System: Consists of proteins that enhance the ability of antibodies and phagocytic cells to clear microbes.
Pattern-Recognition Receptors (PRRs):
- Detect unique antigens in microorganisms.
- Types include membrane-bound (e.g., Toll-like receptors, C-type lectin receptors) and cytoplasmic receptors (e.g., NOD-like receptors, RIG-I-like receptors).

Pattern-Recognition Receptors (PRRs)

Function:
- Recognize non-self antigens (PAMPs and DAMPs).
- Activate immune responses, including opsonization, complement activation, phagocytosis, pro-inflammatory signaling, and apoptosis.
PAMPs (Pathogen-Associated Molecular Patterns): Associated with microbial pathogens, these patterns signal the presence of potential threats.
DAMPs (Damage-Associated Molecular Patterns): Released by host cells during damage, indicating cell stress or death.

Toll-Like Receptors (TLRs)

A subset of PRRs, these proteins are essential for detecting microbial components post-barrier breach.
Found on various immune and non-immune cells, including dendritic cells, macrophages, and epithelial cells.
Recognize structurally conserved microbial molecules, leading to immune activation.
Structure: Comprises exterior leucine-rich repeats (LRRs) and an interior TIR (Toll-IL-1 Receptor) domain.
Types: Includes TLR1 to TLR13, with TLR11-13 not present in humans.

NOD-Like Receptors (NLRs)

Cytoplasmic PRRs that detect both PAMPs and DAMPs.
Participate in signal transduction and share structural similarities with TLRs.
Comprise 23 family members, characterized by three domains: LRR, NACHT, and effector binding (EBD).

C-Type Lectin Receptors (CLRs)

Surface receptors found on various immune cells: monocytes, macrophages, dendritic cells, etc.
Recognize carbohydrate components from fungi, bacteria, viruses, parasites, and allergens.
Major human CLRs include receptors for mannose, fucose, and glucans, facilitating immune signaling and phagocytosis.

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Description

Explore the diverse types of biologically active soluble molecules involved in both innate and adaptive immune responses. This quiz covers key elements such as cytokines, antibodies, and complements, and their roles in immunity. Test your knowledge on how these molecules contribute to our body's defense mechanisms.