Immune Function and Inflammatory Responses

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Questions and Answers

What is the primary function of the immune system?

To prevent or eradicate infections (correct)

To repair tissues after injury

To promote healing of wounds

To provide nutrients to cells

Which characteristic does the inflammatory response NOT possess?

Involves various cells

Specific targeting (correct)

No memory function

Rapid response

What is the role of Human Leukocyte Antigen (HLA) in the immune system?

Distinguishes self from non-self entities (correct)

Promotes inflammation in response to infection

Facilitates the memory function of lymphocytes

Encourages the production of antibodies

Which type of antigen is primarily recognized by lymphocytes?

Molecules recognized by lymphocytes Signup and view all the answers

Which statement about the immune response is correct?

It has a memory capability for faster future responses Signup and view all the answers

What is the primary function of the generation of clonal diversity in the immune response?

To create a population of lymphocytes capable of recognizing all foreign antigens Signup and view all the answers

Where do lymphoid stem cells migrate to differentiate into T cells?

Thymus Signup and view all the answers

Which statement best describes clonal selection in the immune response?

It involves the selection and proliferation of mature B and T cells in response to specific antigens. Signup and view all the answers

What is the end result of the clonal diversity process?

A diverse population of lymphocytes with specificity for various antigens Signup and view all the answers

What role do secondary lymphoid tissues play in the immune system?

They serve as sites for the residence and proliferation of lymphocytes. Signup and view all the answers

What type of vaccine is used to create an immune response by using inactivated bacterial toxins?

Toxoid vaccine Signup and view all the answers

Which type of vaccine involves the use of polysaccharides chemically linked to proteins for activation of T helper cells?

Conjugate vaccine Signup and view all the answers

What type of vaccine may not be safe for immunocompromised individuals due to the presence of live attenuated microbes?

Live attenuated vaccine Signup and view all the answers

What is the primary form of protection elicited by inactivated viruses such as the injected polio vaccine?

Antibody response Signup and view all the answers

Which type of vaccine is synthesized from recombinant proteins in a laboratory setting?

Synthetic vaccine Signup and view all the answers

What additional immune response is typically generated by live attenuated vaccines compared to inactivated vaccines?

Antibody response and T cell response Signup and view all the answers

Which of the following examples is classified as a subunit vaccine?

HPV vaccine Signup and view all the answers

Which type of vaccine is currently being tested in clinical trials for producing responses against several infections?

DNA vaccine Signup and view all the answers

What type of immunoglobulin is primarily produced during the secondary response to an antigen?

IgG Signup and view all the answers

Which T lymphocyte type is responsible for directly attacking and killing cells that bear foreign antigens?

Cytotoxic T cells Signup and view all the answers

What role do Memory T cells (Tm) play in the immune system?

Induce a secondary immune response Signup and view all the answers

Natural Killer cells account for what approximate percentage of the lymphocyte population?

10% Signup and view all the answers

What type of traditional vaccine involves the use of killed virulent microbes?

Inactivated vaccines Signup and view all the answers

Which T lymphocyte type is likely responsible for delayed hypersensitivity reactions?

Lymphokine-producing T cells Signup and view all the answers

Which of the following is NOT a function of Natural Killer cells?

Suppress B cell activation Signup and view all the answers

What is the primary generation result of a first exposure to an antigen?

Production of IgM Signup and view all the answers

What is the primary role of T helper cells in the immune response?

Secrete interleukin-2 to facilitate lymphocyte proliferation Signup and view all the answers

Which of the following statements about B cell differentiation is correct?

B cells proliferate into plasma cells that produce antibodies Signup and view all the answers

Which immunoglobulin class is primarily associated with primary immune responses?

IgM Signup and view all the answers

What happens during clonal expansion of B and T cells?

Selected B and T cells mature and proliferate Signup and view all the answers

What is the function of the Fc fragment of an immunoglobulin?

Activate the complement system Signup and view all the answers

How does the body typically respond to an antigen during the primary immune response?

Slow production of IgM antibodies after a latent period Signup and view all the answers

Which class of immunoglobulin is commonly found in secretions such as saliva and breast milk?

IgA Signup and view all the answers

What is the primary role of antibody-mediated responses?

To promote phagocytosis and neutralize pathogens Signup and view all the answers

Which type of T cells are responsible for cell-mediated destruction of infected cells?

Cytotoxic T cells (Tc) Signup and view all the answers

What is primarily produced by plasma cells derived from B lymphocytes?

Immunoglobulins (antibodies) Signup and view all the answers

Study Notes

Basic Concepts in Immune Function

The primary function of the immune system is to prevent or eradicate infections
Also involved in surveillance and destruction of cancer cells
Immune response can cause cell injury and stimulate pathological inflammation
The immune system recognizes and responds to tissue grafts

Comparison of Inflammatory and Immune Responses

Inflammatory Response (Innate Immunity)
- Rapid
- Nonspecific
- No Memory
- Involves various cells, including neutrophils, monocytes/macrophages, eosinophils, endothelial cells, platelets, and plasma systems
Immune Response (Adaptive Immunity)
- Slower
- Specific
- Memory
- Involves lymphocytes and antibodies
- Can be induced by vaccination

Antigen

A molecule recognized by lymphocytes and reacts with antibodies
Foreign (non-human) antigen
- Viruses
- Bacteria
- Pollens and other environmental allergens
- Food or drugs
Self-antigen
- Human Leukocyte Antigen (HLA)
  - Cell surface proteins distinguishing self from non-self
  - Present on all cell membranes except red blood cells
  - Major Histocompatibility Complex (MHC): a genomic region consisting of four loci on chromosome 6 that directs synthesis of HLA antigen
- RBC antigen (A, B, and Rh Antigen)

Overview of the Immune Response

Two Phases: Generation of Clonal Diversity and Clonal Selection
Generation of Clonal Diversity
- The production of a population of lymphocytes that can recognize all foreign antigens
- Bone marrow produces lymphoid stem cells that migrate to the primary (central) lymphoid organs
  - Thymus
  - Bone Marrow
- Lymphocytes differentiate into immunocompetent (but still immature) T cells or B cells
- The entire population of immunocompetent B and T cells has the ability to recognize all antigens, however each group of B or T cells (clones) has receptor specificity for one specific antigen
- Lymphocytes are released from these organs into the circulation and migrate to secondary lymphoid tissues (e.g., spleen, lymph nodes, mucosal and cutaneous lymphoid tissues)
Clonal Selection
- The selection and proliferation of mature B and T cells in response to exposure to a specific antigen
- Involves antigen processing and presentation by antigen-presenting cells (APCs) to immature lymphocytes
- Immunocompetent B and T cells with receptor specificity are selected and stimulated to mature and proliferate (clonal expansion)
  - B cells differentiate into antibody-producing plasma cells
  - T cells differentiate into cytotoxic and other T cells
- These antigen-selected cells mount a defensive response against the foreign antigen
- Production of B and T memory cells

Induction of the Immune Response

Formation of B and T cells, and antibodies in response to antigen
Steps in Antigen Processing and Presentation
- Macrophage and other antigen presenting cells (e.g., dendritic cells, B cells) phagocytosis of foreign organism or tissue
- Expression of foreign antigen on surface receptors (MHC Class II) of macrophage
- Macrophage produces interleukin-1 (IL-1)
- Antigen presentation to Helper T (Th or CD4) cells: processed antigen on MHC Class II receptor binds to T cell receptor (TCR) on Th (CD4) cell
- Th secretes interleukin-2 (IL-2) which stimulates Th to mature into functional Th1 and Th2 cells
- IL-2 secreted by Th1 and Th2 cells also stimulates proliferation and differentiation of lymphocytes:
  - B lymphocytes (stimulated by Th2 cells)
    - B cells proliferate and differentiate into plasma cells
    - Plasma cells produce antibodies
  - T lymphocytes (stimulated by Th1 cells)
    - Cytotoxic T (Tc or CD8 T cells) cells proliferate and are responsible for cell-mediated destruction
    - Memory Cells (B and T memory cells are also formed)

B Lymphocyte Response

Also called the humoral response
Bursal bound (immunocompetent) B cells are activated by T helper cells
Postbursal B cells (plasma cells) produce immunoglobulins (antibodies)
Immunoglobulins are glycoproteins produced by plasma cells
- Immunoglobulin: term used to denote all types
- Antibody: Immunoglobins that have specificity for a particular antigen
Structure of Immunoglobulins
- Antigen-binding fragment (Fab)
  - Contains recognition sites (receptors) for antigenic determinants
  - Confers specificity
- Crystalline fragment (Fc)
  - Provides biologic function by activation of the complement system and inflammatory cells
  - Informs inflammatory mediators that the antigen has invaded the body

Antibody Classes

Have antigenic, structural, and functional differences
- IgM - general antibody, highest titers present during primary immune responses
- IgG - general antibody, highest titers present during secondary immune responses
- IgA - preformed antibody found in sweat, saliva, tears, and breast milk
- IgE - antibody produced during allergic responses (type I hypersensitivity reactions)

Function of Antibodies

Begins with antigen binding to form antigen-antibody complexes
- Neutralize bacteria and viruses
- Promotes phagocytosis of bacteria and viruses (opsonization)
- Activate the complement cascade

Primary and Secondary Immune Responses

Confer active acquired immunity
Primary: antigenic challenge with production of measurable immunoglobins (antibodies), primarily IgM, after a latent period of about 5 days.
Secondary: a second antigen challenge with more rapid and larger production of immunoglobins, primarily IgG.

T Lymphocyte Response

Also called the cellular response
Cytotoxic T cells (Tc): Attack antigen directly and kill cells bearing foreign antigen
Memory T cells (Tm): Induce secondary immune response

Other Types of T Lymphocytes

Lymphokine-producing T cell (Td): Likely a Th1 cell that is responsible for delayed hypersensitivity reactions
Regulatory T cell (Treg): Develop in the thymus or peripheral tissues and suppress B cell and T cell activation

Natural Killer Cells

Arise from the lymphoid stem cell lineage
Account for ~ 10% of the lymphocyte population
Recognize virally infected or stressed cells and once activated release interferon-gamma which helps macrophages kill the infected cell
Can also engage in direct cell killing of virally infected and cancer cells

Vaccination

A process of stimulating a protective immune response against microbes through exposure to nonpathogenic forms or components of the microbes

Types of Traditional Vaccines

Most traditional vaccines mainly stimulate the B lymphocyte (i.e., antibody) response
Inactivated
- Virulent microbes are killed to abolish their infectivity and pathogenicity, yet still retain their immunogenicity
- Large, multiple doses are often required
- Booster vaccinations are required
Live attenuated
- Microbes are treated to reduce their infectivity and pathogenicity, yet still retain their immunogenicity
- May not be safe for immunocompromised individuals
- Boosters are required less often
Toxoid
- Vaccine is made from inactivated bacterial toxin
Subunit vaccines
- The vaccine is comprised of microbial proteins and/or polysaccharides that stimulate the immune system
Conjugated vaccines
- Microbial polysaccharides are chemically coupled with proteins so that they can stimulate Th cells
Synthetic vaccines
- Antigens are formed from recombinant proteins and other molecules in a laboratory environment

Types of Vaccines and Forms of Protection

Type of Vaccine
- Inactivated or killed virus
- Inactivated or killed bacteria
- Live attenuated virus
- Live attenuated bacteria
- Toxoid
- Subunit (antigen) vaccines
- Conjugate vaccines
- Synthetic vaccines
- Viral vectors
- DNA vaccines
Examples
- Injected polio, hepatitis A
- Cholera, bubonic plague, pertussis
- Measles, mumps, rubella, varicella, flu, oral polio, rabies
- BCG vaccine for TB
- Tetanus toxoid, diphtheria toxoid, rattlesnake venom
- HPV
- H.influenza type B
- Hepatitis B, H1N1
- Clinical trials of HIV antigen in canary pox vector
- Clinical trials ongoing for several infections
Form of protection
- Antibody response
- Antibody response and T cell response
- Antibody response and T cell response
- Antibody response
- Antibody response
- Antibody response
- Th response
- Antibody response
- Antibody response and T cell response
- Antibody response and T cell response

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Description

This quiz covers the essential concepts of immune function, including the differentiation between innate and adaptive immunity. It explores how the immune system responds to infections and the role of antigens in immune responses. Test your understanding of these critical biological processes!