Innate Immunity Overview

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Questions and Answers

What is the primary role of IgG antibodies in the immune system?

Initiate the first immune response to infection

Bind to antigens and prevent microbial attachment

Trigger complement and enhance phagocytosis (correct)

Primarily involved in blood typing

Which of the following correctly describes IgM antibodies?

Pentamer made of 5 monomers held with a J chain (correct)

The most abundant antibody in serum

Produced only after exposure to antigens

Primarily found in mucous membranes

Which characteristic is true about IgA antibodies?

They are the most common serum antibodies

They consist of both monomer and dimer forms (correct)

They trigger complement fixation

They are exclusively found in the blood

What is a function of IgE antibodies?

They cause the release of histamine during allergic reactions Signup and view all the answers

What happens to self-reactive B cells during maturation?

They undergo clonal deletion Signup and view all the answers

Where are B cells primarily produced?

Red bone marrow Signup and view all the answers

What is a distinguishing feature of IgD in the immune system?

It might eliminate self-reactive B cells Signup and view all the answers

What percentage of serum antibodies is comprised by IgM?

6% Signup and view all the answers

What mechanism does the alternative pathway use to activate C3?

Combination of C3 with factors B, D, and P on microbe surface Signup and view all the answers

What is the primary function of interferon IFN-y?

Stimulating the production of nitric oxide by neutrophils and macrophages Signup and view all the answers

Which outcome of complement activation involves the creation of a membrane attack complex?

Cytolysis Signup and view all the answers

Which protein is NOT related to iron binding in humans?

Siderophore Signup and view all the answers

What initiates the lectin pathway for complement activation?

The production of cytokines by macrophages Signup and view all the answers

Which of the following statements about iron competition is true?

Humans have multiple proteins that bind to iron and limit its availability to pathogens. Signup and view all the answers

Which of the following components is NOT involved in the classical or alternative pathways of complement activation?

Iron Signup and view all the answers

What role do cytokines play in the immune response according to the content?

They stimulate the production of mannose-binding lectin. Signup and view all the answers

What is the primary role of neutrophils during inflammation?

To migrate and perform phagocytosis Signup and view all the answers

What triggers vasodilation during the inflammatory response?

Release of histamine Signup and view all the answers

What must occur before tissue repair can be completed?

All harmful substances must be removed Signup and view all the answers

Which of the following describes the complement system?

Over 30 serum proteins working to destroy microbes Signup and view all the answers

Which pathway of the complement system is activated by the adaptive immune response?

Classical pathway Signup and view all the answers

What is the role of C3b in the complement system?

Functions in opsonization and cytolysis Signup and view all the answers

How does a fever affect the body's response to infection?

Initiates shivering and vasoconstriction Signup and view all the answers

What is the primary function of macrophages during inflammation?

Perform the primary phagocytosis after neutrophils Signup and view all the answers

What is the primary function of antimicrobial peptides in the immune response?

They destroy DNA and RNA of pathogens. Signup and view all the answers

What is a defining characteristic of cellular immunity?

It can involve the destruction of infected target cells. Signup and view all the answers

How does the adaptive immune response differ between primary and secondary responses?

The secondary response develops memory cells. Signup and view all the answers

What role do cytokines play in the immune system?

They act as messengers between immune cells. Signup and view all the answers

What is meant by the term 'haptens' in immunology?

Haptens are too small to trigger an immune response without a carrier. Signup and view all the answers

What is the primary role of interleukins within the cytokine family?

They facilitate communication among leukocytes. Signup and view all the answers

What does the term 'valence' refer to in the context of antibodies?

The number of antigen-binding sites on an antibody. Signup and view all the answers

What can lead to a cytokine storm in the immune system?

Overproduction of certain cytokines. Signup and view all the answers

Which of the following statements about hemolysins is correct?

They destroy red blood cells and gather released iron. Signup and view all the answers

What is the function of T lymphocytes in the adaptive immune system?

They can either kill infected cells or secrete cytokines. Signup and view all the answers

What is not a characteristic of innate immunity?

Targets specific pathogens Signup and view all the answers

What process involves the coating of a microorganism with serum proteins to enhance phagocytosis?

Opsonization Signup and view all the answers

Which line of defense includes inflammation and fever?

Second line of defense Signup and view all the answers

What is the primary role of cytokines in the immune response?

Recruit other white blood cells Signup and view all the answers

What is the role of lysozyme in innate immunity?

Destroys bacterial cell walls Signup and view all the answers

Which statement about adaptive immunity is true?

It targets specific pathogens Signup and view all the answers

How do mucous membranes contribute to the immune system?

They provide a physical barrier and trap microbes Signup and view all the answers

Which type of white blood cell primarily works in early stages of infection?

Neutrophils Signup and view all the answers

Which component of the immune system helps in the activation of B and T cells?

Cytokines Signup and view all the answers

What is the function of the mucociliary escalator?

Transport microbes trapped in mucus from the lungs Signup and view all the answers

What is a characteristic of granulocytes?

They have visible granules in their cytoplasm Signup and view all the answers

What does fever primarily enhance in the body?

Inflammatory response Signup and view all the answers

What is the role of the lymphatic system in immunity?

Filters blood plasma and transports pathogens to lymph nodes Signup and view all the answers

What triggers the immune response in the first line of defense?

Toll-like receptors binding to PAMPs Signup and view all the answers

What is the primary function of CD4+ T helper cells?

Regulate antibody production Signup and view all the answers

Which type of immune response do live attenuated vaccines primarily stimulate?

Both cellular and humoral responses Signup and view all the answers

What triggers the release of perforin by cytotoxic T lymphocytes?

Recognition of infected self-cells with MHC class I molecules Signup and view all the answers

Which of these does NOT function as an antigen-presenting cell?

T regulatory cells Signup and view all the answers

What type of immune response is characteristic of T-independent antigens?

Weak IgM production without memory cell formation Signup and view all the answers

What is the role of natural killer (NK) cells in immune response?

Destroying cells that do not express MHC class I molecules Signup and view all the answers

Which reaction occurs during Type II hypersensitivity?

Complement activation by IgG or IgM antibodies bound to cells Signup and view all the answers

In autoimmune diseases, what occurs when the immune system loses self-tolerance?

Destruction of self-tissues Signup and view all the answers

What is the main characteristic of conjugated vaccines?

Combine an antigen with a protein to enhance the immune response Signup and view all the answers

During an HIV infection, what occurs in the latent phase?

The virus remains hidden within the host's chromosome Signup and view all the answers

What type of immunity is provided by maternal antibodies transferred through the placenta?

Naturally acquired passive immunity Signup and view all the answers

What are the main components of the human immunodeficiency virus (HIV)?

RNA, reverse transcriptase, and gp120/gp41 spikes Signup and view all the answers

Which of the following describes the process of agglutination in diagnostic tests?

Formation of visible clumps when antibodies bind to large antigens Signup and view all the answers

Study Notes

Innate Immunity

Three lines of defense against pathogens
- First line: skin, mucous membranes, antimicrobial substances
- Second line: inflammation, fever, phagocytes
- Third line: humoral and cellular immunity
Two lines work together if a microbe enters
- Second line is fast
- Third line is slow
Immunity is resistance to disease; susceptibility is lack of resistance
Innate immunity is rapid, present at birth, and has no memory; it does not target specific microbes.
First line of defense: physical barriers and secretions
- Skin: dry, salty, acidic, exfoliation, normal flora
- Mucous membranes: line GI, respiratory, and GU tracts; prevent microbes from drying out; trap microbes with viscous glycoproteins
- Secretions
  - Lacrimal apparatus: tears, IgA
  - Saliva: lysozyme, IgA
  - Cerumen: ear wax
  - Urine
  - Vaginal secretions

Chemical factors

Sebum: protective film; lowers pH
Lysozyme: in perspiration, tears, saliva, urine; destroys bacterial cell walls
Gastric juice: low pH, destroys most bacteria and toxins
Vaginal secretions: low pH, inhibits microbial growth

Granulocytes and Agranulocytes

Granulocytes: visible granules in cytoplasm
- Neutrophils (PMNs): phagocytic, early infection
- Basophils: allergic response, inflammation
- Eosinophils: slightly phagocytic, toxic against parasites and helminths
Agranulocytes: granules not visible with light microscope
- Monocytes: mature into macrophages in tissues, phagocytic
- Dendritic cells: in skin, mucous membranes, thymus, phagocytic
- Lymphocytes: T cells, B cells, NK cells; adaptive immunity

Lymphatic System

Filters blood plasma, returning to circulatory system
Lymph vessels carry lymph and possible microbes to lymph nodes
Lymphocytes and macrophages destroy pathogens in lymph nodes

Phagocytes

Fixed macrophages: residents of tissues/organs
Dendritic cells: skin, liver, etc.
Kupffer cells: liver
Microglial cells: nervous system
Free/wandering macrophages: roam tissues, gather at infection sites

Phagocytosis Mechanism

Chemotaxis: chemical signals attract phagocytes

Adaptive Immunity

Adaptive immunity: specific defenses against particular pathogens, with a "memory"
Humoral immunity: B lymphocytes; produce antibodies

Cellular Immunity

T lymphocytes; recognize processed antigens; destroy target cells or release cytokines

Cytokines

Chemical messengers of immune cells
Promote or regulate immune responses.

Antibodies

Proteins that bind to antigens; specific for a particular antigen
Involved in different responses like Neutralization, complement activation/ lysis, etc
Different classes (e.g., IgG, IgM, IgA) with different functions.

Immunological Memory

Secondary immune response is faster and stronger than primary if exposed to the same pathogen

Hypersensitivity Reactions

Immune system overreacts to harmless antigens
Type I (anaphylactic): IgE-mediated; rapid response
Type II (cytotoxic): IgG/ IgM-mediated; cell destruction
Type III (immune complex): immune complex deposition; inflammation
Type IV (delayed cell-mediated): T cell-mediated; delayed response

Immune System Disorders

Immunodeficiencies: impaired immune responses; congenital or acquired
Hypersensitivities: undesirable immune system responses to antigens

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Description

Explore the essential components of innate immunity in this quiz. Learn about the three lines of defense against pathogens, the roles of physical and chemical factors, and how these defenses work together to protect the body from diseases. Dive into the rapid and non-specific nature of innate immunity.