Innate Immune System Overview
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Questions and Answers

Which of the following best describes the function of DAMPs?

  • To recognize and respond to specific microbial products necessary for cell survival.
  • To identify damaged tissue and trigger immediate immune responses. (correct)
  • To initiate signal transduction pathways when bound to toll-like receptors.
  • To target and eliminate pathogens through phagocytic activity.

What is the primary function of 'toll-like receptors'?

  • To promote the expansion of immune cell populations.
  • To directly destroy pathogens through phagocytosis.
  • To trigger signal transduction upon binding to specific ligands. (correct)
  • To act as a physical barrier, preventing microbes from entering the body.

Which statement accurately describes the recognition process involving microbial products?

  • Microbial products are specifically targeted by soluble receptors floating in plasma.
  • Microbial products are recognized by receptors that are essential for cell survival. (correct)
  • Microbial products are recognized by DAMPs, initiating an adaptive immune response.
  • Microbes recognize endogenous molecules produced by damaged or dying cells.

Why is memory not explicitly mentioned as an attribute of the innate response in the text provided?

<p>Because innate responses do not generate long-term immunological memory. (B)</p> Signup and view all the answers

Which of the following describes the distinction between PAMPs and DAMPs?

<p>PAMPs are microbial products, while DAMPs are released from damaged or dying cells. (C)</p> Signup and view all the answers

According to the information given, what is a key feature of some immune receptors?

<p>They are soluble and readily float around in plasma. (C)</p> Signup and view all the answers

What does the text suggest about the 'specificity' of immune responses?

<p>Innate immune responses like those involving toll-like receptors, tend to be less specific, targeting broad classes of pathogens (A)</p> Signup and view all the answers

Which of the following is most likely associated with the recognition of fungal infections?

<p>A new type of receptor typically recognizing fungi. (A)</p> Signup and view all the answers

Flashcards

DAMPs

Immune cells recognize damage-associated molecular patterns (DAMPs) released from injured or dying cells. These patterns are specific to damaged tissues and trigger an immediate immune response.

Pattern Recognition Receptors (PRRs)

Pattern recognition receptors (PRRs) are proteins found on the surface of immune cells that recognize specific molecules associated with pathogens (PAMPs) or damaged cells (DAMPs). Recognition of these patterns triggers a signal transduction pathway, leading to an immune response.

Toll-like Receptors (TLRs)

Toll-like receptors (TLRs) are a type of PRR that are expressed on the cell surface or in the cytoplasm of immune cells. They play a crucial role in recognizing PAMPs and DAMPS, leading to the activation of immune responses.

Cytoplasmic Receptors

Cytoplasmic receptors are PRRs located within the cytoplasm of immune cells. They are typically involved in detecting intracellular pathogens, such as viruses, and triggering an immune response.

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Soluble Receptors

Soluble receptors are PRRs that circulate in the blood and lymph. They can bind to PAMPs or DAMPS, triggering an immune response without needing to be attached to a cell.

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Phagocytic Receptors

Phagocytic receptors are specialized PRRs found on the surface of phagocytic cells, such as macrophages and neutrophils. They facilitate the engulfment and destruction of pathogens.

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Receptor Diversity in Immune Response

The immune system relies on a diverse range of receptors to detect and respond to threats. Each receptor type has its own unique mechanism of activation, recognition targets, and downstream signaling pathways.

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Importance of PRR Diversity

The immune system's ability to respond to a vast range of pathogens and damaged cells is crucial for protecting us from disease. Understanding the different PRR types and their functions is essential for comprehending the intricacies and complexity of the immune response.

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Study Notes

Innate Immune System & Inflammation

  • The innate immune system is the body's first line of defense against pathogens
  • It's evolutionarily conserved and generates rapid, non-specific inflammatory responses
  • This system responds to signals from pattern recognition receptors (PRRs) recognizing pathogen-associated molecular patterns (PAMPs)
  • PRRs also recognize damage-associated molecular patterns (DAMPs) in the host

Key Components of Innate Immunity

  • Neutrophils: A type of phagocyte that quickly migrate to sites of infection
  • Natural Killer (NK) cells: Lymphocytes that destroy virus-infected cells by inducing apoptosis; monitor MHC proteins
  • Macrophages: Patrol tissues, are the first to encounter pathogens, and mediate phagocytosis
  • Dendritic cells: Present antigens to lymphocytes
  • Mast cells: Involved in allergic reactions and inflammation

Innate Immunity vs Adaptive Immunity

  • Innate immunity is immediate, non-specific, and has no memory
  • Adaptive immunity is slower, specific, and has memory

How Innate Immunity Distinguishes Self from Non-Self

  • Relies on recognition of pathogen-associated immunostimulants (PAMPs) that are common to many pathogens but absent in the host
  • Microbes have structures like flagella, LPS, and nucleic acids that mammalian cells lack; these are used for recognition
  • Formylated methionine is often the first amino acid in bacteria, distinguishing them from host cells
  • Specific short sequences in bacterial DNA, such as CpG motifs, are less common in vertebrates

Pathogen Recognition Receptors (PRRs)

  • PRRs are proteins that recognize molecules common to pathogens
  • Include toll-like receptors (TLRs), NOD-like receptors (NLRs), RIG-I-like receptors (RLRs), C-type lectin receptors (CLRs), and AIM2-like receptors (ALRs)
  • Different PRRs are associated with different locations within the cell (i.e., membrane-bound vs intracellular)

Complement System

  • A group of about 20 interacting soluble proteins that complement antibody function
  • Some complement proteins are PRRs
  • Plays a critical role in activating the inflammatory response, opsonization, and cell lysis of pathogens

Inflammation

  • Tissue response to pathogens, allergies, or injuries
  • Primary goal: to destroy foreign invaders and initiate tissue repair
  • Characterized by redness, swelling, heat, and pain (edema, increased blood flow)
  • Involves vasodilation, increased vascular permeability, recruitment of immune cells, phagocytosis, and tissue repair

Phagocytosis

  • Process where cells engulf and destroy pathogens
  • Mediated by PRRs
  • Involves activating actin polymerization and engulfing pathogens within phagosomes
  • Neutrophils are key phagocytes

Role of NK Cells

  • Bridge between innate and adaptive immunity
  • Destroy virus-infected cells and some cancer cells
  • Monitor MHC proteins for abnormal cell activity

Summary of Innate Immunity

  • Crucial in priming the adaptive immune response
  • Intact skin and mucous membranes form the first and most important defense
  • Pathogen recognition receptors (PRRs) are activated when these barriers are breached, leading to inflammation and phagocytosis

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Lecture 2.0 - Innate Immune System Notes 2025 PDF

Description

This quiz explores the innate immune system, highlighting its key components and comparing it with adaptive immunity. Understand the roles of various immune cells such as neutrophils, macrophages, and natural killer cells, and learn how they respond to pathogens and inflammation.

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