Immunology Overview: Antibody Classes and Responses

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Questions and Answers

Which of the following are properly matched? (Select all that apply)

IgA: first antibody released during primary immune response

IgG: most abundant antibody (correct)

IgM: secreted in tears

IgE: main antibody of the secondary immune response

Antibodies typically act extracellularly in body fluids and are therefore considered part of the humoral branch of adaptive immunity.

True

A person with a deficit of IgA is likely to exhibit recurrent respiratory tract infections. Which of the following correctly explains the role of IgA in this scenario?

IgA is the most abundant antibody in the plasma and plays a central role in protecting against bacterial infections on our body surfaces

IgA functions as a B cell antigen receptor; without these receptors B cells are unable to protect us against pathogens on our body surfaces

IgA triggers release of histamine from cells in our mucous membranes, which is required for an inflammatory response to infection

IgA, found in the mucus lining of the respiratory tract, helps stop pathogens from attaching to epithelial surfaces and entering our body (correct)

T-cell activation requires _________.

antigen binding and co-stimulation Signup and view all the answers

Which molecules of the adaptive defense system provide humoral immunity by circulating freely in the blood and lymph, where they bind to extracellular antigens and inactivate them and mark them for destruction?

antibodies Signup and view all the answers

Which of the following statements does not describe the adaptive immune response?

It occurs immediately after the body is challenged by foreign material Signup and view all the answers

Which of these mechanisms do cytotoxic T cells use to destroy a target?

perforation of the membrane Signup and view all the answers

Clonal selection of B cells _________.

results in formation of plasma cells Signup and view all the answers

B cells respond to the initial antigen challenge by _____________.

producing progeny cells that include plasma cells and memory cells Signup and view all the answers

Which of the following should produce naturally acquired, active immunity?

recovering from the chicken pox Signup and view all the answers

How many sites on this antibody molecule have potential to bind to a non-self molecule?

2 Signup and view all the answers

Which of the following statements regarding the primary versus the secondary immune response is true?

A primary response results when naive lymphocytes are activated, while a secondary response is a result of activating memory cells. Signup and view all the answers

The primary immune response ________.

has a lag period while B cells proliferate and differentiate into plasma cells. Signup and view all the answers

What types of antigen do mature T cells normally not recognize?

self-antigens Signup and view all the answers

Why are children given vaccinations?

so that they will develop antibodies against various disease-causing pathogens Signup and view all the answers

Proliferation of lymphocytes occurs immediately after which of these events?

activation Signup and view all the answers

Which immunoglobulin class is the most abundant antibody in plasma?

IgG Signup and view all the answers

How does a lymphocyte exhibit immunocompetence?

by being able to recognize their one specific antigen Signup and view all the answers

Tissue rejection after an organ transplant is least likely due to the action of _________.

regulatory T cells Signup and view all the answers

Which of the following does NOT correctly describe the process of CD4 T cell activation and proliferation?

The CD4 T cell's antigen receptor binds to a class I MHC on the surface of an antigen presenting cell. Signup and view all the answers

The antivenom used to treat a venomous snake bite is an antibody produced in an animal such as a horse. How would you classify the resulting humoral immunity?

passive immunity, artificially acquired Signup and view all the answers

Which of the following is NOT a type of T cell?

antigenic Signup and view all the answers

Which of the following statements regarding NK cells is a false or incorrect statement?

NK cells are a type of neutrophil. Signup and view all the answers

In clonal selection of B cells, which substance is responsible for determining which cells will eventually become cloned?

antigen Signup and view all the answers

Where does most exogenous antigen presentation take place?

in lymphoid tissues and organs Signup and view all the answers

Which of the following is associated with passive immunity?

passage of IgG antibodies from a pregnant mother to her fetus Signup and view all the answers

Which of the following cells engulf antigens by phagocytosis and present fragments of them on their own surfaces for recognition?

dendritic cells Signup and view all the answers

Which lymphocytes act as the bridge between the cellular and humoral responses?

helper T cells Signup and view all the answers

An advantage to adaptive immunity is ________.

its memory cells that provide quicker, larger and more efficient immune response upon second and subsequent exposure to an antigen Signup and view all the answers

Which of the following examples below describes an autoimmune disease?

Antibody binding to acetylcholine receptors of the motor end plate resulting in muscle weakness. Signup and view all the answers

Which of the following best illustrates artificially acquired active humoral immunity?

vaccines Signup and view all the answers

What type of T cell can directly attack and kill other cells, such as virus-infected cells?

cytotoxic T cells Signup and view all the answers

IgA?

Protects mucosal barriers Signup and view all the answers

IgE?

Involved in allergies Signup and view all the answers

IgM?

First to peak during a primary immune response Signup and view all the answers

IgG?

Main antibody of both primary and secondary immune response. Signup and view all the answers

IgD?

Along with IgM, this is a B cell receptor. Signup and view all the answers

A vaccine is effective because __________.

the secondary response of the adaptive immunity is faster and more efficient than the primary response Signup and view all the answers

Which mechanism(s) of antibody action result(s) in cell lysis?

complement activation Signup and view all the answers

Which class of tissue graft is the LEAST likely to be accepted by a patient's body?

xenograft Signup and view all the answers

Vaccines work by ________.

priming the adaptive immunity with a relatively harmless primary exposure Signup and view all the answers

Study Notes

Antibody Classes

IgG: Most abundant antibody in plasma; crosses placenta to protect fetus.
IgA: Protects mucosal surfaces; major in secretions like saliva and tears; prevents pathogen attachment.
IgE: Involved in allergic reactions; triggers histamine release.
IgM: First antibody to respond during the primary immune response; found on B cells.
IgD: Serves as a B cell receptor, along with IgM.

Immune Response Characteristics

Humoral immunity is mediated by antibodies acting extracellularly in body fluids.
Primary immune response has a lag period, while secondary response is faster due to memory cells.
Adaptive immune response is specific, systemic, and has memory.

T Cell Functionality

T cell activation requires both antigen binding and co-stimulation.
Cytotoxic T cells perforate target cell membranes, leading to cell death.
Helper T cells bridge the humoral and cellular immune responses.

B Cell Mechanisms

Clonal selection results in the formation of plasma and memory cells.
B cells respond to antigens by generating progeny that include both plasma and memory cells.

Types of Immunity

Active Immunity: Develops through exposure to a pathogen or vaccination (e.g., recovering from chickenpox).
Passive Immunity: Provided through external sources (e.g., maternal antibodies or antivenom); can be artificially acquired.

Antigen Presentation

Dendritic cells engage in phagocytosis and present antigens to T cells in lymphoid tissues.
Mature T cells do not recognize self-antigens due to negative selection during development.

Therapeutic Interventions

Vaccinations prime the immune system for a faster and more efficient response to pathogens.
Antivenoms provide temporary immunity through the introduction of antibodies produced in other animals.

Immunology Concepts

Memory Cells: Enhance rapid responses on subsequent encounters with antigens.
Cytotoxic T Cells: Directly kill infected or abnormal cells by recognizing specific antigens.

Transplant Immunology

Xenografts (species-to-species transplants) have a high failure rate due to immune rejection.

Immune System Dynamics

Activation of lymphocytes occurs post-antigen binding, leading to proliferation.
Antibody mechanisms include complement activation, agglutination, and neutralization for pathogen elimination.

Immune System Type Characteristics

The immune response is robust and relies on a network of interactions among lymphocytes, antibodies, and antigen-presenting cells to effectively defend against pathogens.

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Description

Explore the various classes of antibodies including IgG, IgA, IgE, IgM, and IgD, and their roles in the immune response. Understand the mechanisms of humoral and cellular immunity, T cell functionality, and B cell activation. This quiz will test your knowledge on immunological concepts critical to understanding the immune system.