Immunology Basics: Active vs Passive Immunity

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Questions and Answers

What is a primary characteristic of innate immunity?

It eliminates pathogens rapidly. (correct)

It requires a lengthy activation period.

It is specific to different pathogens.

It develops a memory specific to pathogens.

Which type of immunity includes the ability to develop specifically tailored responses to pathogens?

Adaptive immunity (correct)

Cell-mediated immunity

Innate immunity

Humoral immunity

Which of the following is NOT a component of innate immunity?

T-cell receptors (correct)

Natural killer cells

Neutrophils

Mast cells

What is a primary role of chemokines in the immune system?

To stimulate chemically-induced migration of leukocytes. Signup and view all the answers

Which function is associated with soluble mediators in innate immunity?

Induction of acute inflammatory response. Signup and view all the answers

What distinguishes an immunogen from an antigen?

An immunogen can provoke an immune response, while an antigen merely binds to antibodies. Signup and view all the answers

Which of the following statements about adaptive immunity is accurate?

It can be re-activated if a sustained threat exceeds a certain threshold. Signup and view all the answers

How do interferons function in the immune response?

They increase resistance to viral replication. Signup and view all the answers

What is the role of memory T-cells in the immune response?

They form a rapid response upon re-exposure to the same pathogen. Signup and view all the answers

What leads to the destruction of cells that recognize 'self' during T-cell maturation?

A selection process during maturation in the thymus. Signup and view all the answers

Which sequence correctly orders the phases of the immune response?

Recognition, Amplification, Effector, Termination, Memory Signup and view all the answers

What distinguishes primary immunodeficiency from secondary immunodeficiency?

Primary immunodeficiency is an inherent defect, whereas secondary results from other diseases. Signup and view all the answers

Which of the following is NOT a source of iatrogenic immunodeficiency?

Autoimmunity medications Signup and view all the answers

What distinguishes active immunity from passive immunity?

Active immunity is generated by the immune system after exposure to an antigen; passive immunity is acquired through transfer of antibodies. Signup and view all the answers

Which immunoglobulin class is primarily involved in allergic reactions?

IgE Signup and view all the answers

Which function is NOT associated with IgG antibodies?

Majority in mucosal secretions Signup and view all the answers

What is the first step in the process of cell-mediated immunity?

Antigens are phagocytosed by macrophages and dendritic cells. Signup and view all the answers

Which of the following statements about antibodies is false?

The fragment antigen binding site has a fixed structure. Signup and view all the answers

In which scenario is natural passive immunity gained?

A newborn receiving antibodies through breast milk. Signup and view all the answers

How does IgA function in the immune response?

It is found in mucosal membranes, preventing pathogen adherence. Signup and view all the answers

Which of the following best describes passive immunity?

It can be acquired through the transfer of sensitized lymphocytes. Signup and view all the answers

Study Notes

Immune System Overview

Immune system comprises innate and adaptive immunity.

Innate Immunity

Non-specific defense mechanism against pathogens.
Acts quickly to eliminate pathogens.
Initiates and supports adaptive immunity.
Collaborates with adaptive responses to enhance pathogen elimination.

Adaptive Immunity

Specific response tailored to individual pathogens.
Develops memory to facilitate faster response upon re-exposure.
Requires pre-activation, taking days to weeks.
Continuously evolves throughout an individual's life.

Key Components of Innate Immunity

Exterior Defenses:
- Epithelial barriers, mucosa, and secretions protect from pathogens.
Cellular Components:
- Includes natural killer cells, neutrophils, monocytes/macrophages, eosinophils, basophils, mast cells, and platelets.
Soluble Mediators:
- Complement: Protein system inducing inflammation and enhancing phagocytosis.
- Cytokines: Proteins modifying cellular behavior and communications.

Types of Cytokines

Chemokines:
- Small cytokines promoting leukocyte migration; increase vascular permeability and blood flow.
Interferons:
- Secreted by virus-infected cells; increase resistance to viral replication.
Acute Phase Proteins:
- Pro-inflammatory cytokines affecting metabolism, blood flow, and protein production.

Adaptive Immunity Components

Humoral Immunity:
- Mediated by antibodies in the bloodstream.
Cell-Mediated Immunity:
- Involves T-cells targeting infected or abnormal cells.

Antigens vs. Immunogens

Antigens:
- Molecules that bind to antibodies or T-cell receptors.
Immunogens:
- Antigens that elicit an immune response; e.g., adjuvants enhance vaccine responses.

Active vs. Passive Immunity

Active Immunity:
- Long-lasting protection post-exposure to antigens; includes natural and artificial immunity (vaccines).
Passive Immunity:
- Temporary immunity via transferred antibodies; arises naturally (e.g., breastfeeding) or artificially (e.g., antibody injections).

Antibody Structure and Function

Produced by B lymphocytes.
Comprised of binding sites with variable regions for antigen specificity and constant regions for structural support.

Major Immunoglobulin (Ig) Classes

IgM:
- First responder in immune reactions; activates complement system.
IgG:
- Major antibody for bacteria/viruses; long-lasting, crosses placenta.
IgA:
- Predominant in mucosal areas; found in secretions, protects mucosal surfaces.
IgE:
- Associated with allergies and parasite responses; binds to mast cells.
IgD:
- Functions as an antigen receptor on naive B cells.

Clinical Relevance of Cell-Mediated Immunity

Critical in defending against intracellular pathogens.
Involves processes like tissue transplant rejection and some autoimmune diseases.

Process of Cell-Mediated Immunity

Antigen uptake by macrophages/dendritic cells.
Antigen presentation to T-cells in lymph nodes.
T-cells activated upon matching T-cell receptors, leading to clonal expansion.
Memory T-cells form for accelerated response to subsequent exposures.

Formation of T-Lymphocytes

Stem cells migrate from bone marrow to the thymus for maturation.
T-cell receptors develop; cells recognizing self-antigens are eliminated to prevent autoimmune issues.

Formation/Maturation of B-Lymphocytes

B-cells exit bone marrow expressing IgM and IgD.
Upon activation by antigens, B-cells proliferate and produce antibodies.
Eventually differentiates into plasma cells and memory B cells for swift secondary responses.

Phases of the Immune Response

Recognition: Detecting antigens.
Amplification: Increasing immune cell response.
Effector: Active elimination of pathogens.
Termination: Concluding the immune response.
Memory: Retaining immunity for quicker future responses.

Immunodeficiencies

Primary Immunodeficiency:
- Inherent deficits in T-cells or B-cells; often congenital.
Secondary Immunodeficiency:
- Resulting from other diseases hindering immune function.

Iatrogenic Immunodeficiency Sources

Cytotoxic drugs, corticosteroids, immunosuppressive drugs, radiation therapy, splenectomy.

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Description

This quiz delves into fundamental concepts of immunology, specifically focusing on the differences between active and passive immunity. It discusses mechanisms of immunity, including natural and artificial examples. Test your understanding of how vaccines and exposure to pathogens contribute to immune response.