Immunology Quiz: Antibodies and Humoral Immunity

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Questions and Answers

What structure on an antibody binds specifically to an epitope on an antigen?

Paratope (correct)

Variable region

B cell receptor

Constant region

What is the main function of the humoral immune system?

Engulfing pathogens

Producing antibodies (correct)

Producing cytokines

Activating T cells

What is the role of the B cell receptor (BCR) on B cells?

Directly bind to pathogens

Facilitate phagocytosis

Facilitate B cell activation (correct)

Activate T cells

Which immunoglobulin has a pentameric structure?

IgM Signup and view all the answers

How many polypeptide chains does a basic antibody monomer consist of?

Four chains Signup and view all the answers

What defines the class of an antibody?

The type of heavy chain Signup and view all the answers

Which of the following is NOT a type of mammalian immunoglobulin heavy chain?

Undetermined chain Signup and view all the answers

What component is added to antibodies that classifies them as glycoproteins?

Sugar chains Signup and view all the answers

What is the primary characteristic that distinguishes acquired immunity from innate immunity?

Acquired immunity is created in response to exposure to a foreign substance. Signup and view all the answers

Which of the following describes passive immunity?

Immunity is obtained by receiving preformed antibodies from another source. Signup and view all the answers

Which type of acquired immunity is provided by vaccinations?

Artificial active immunity Signup and view all the answers

What is a common feature of both active and passive immunity?

Both types can be natural or artificial. Signup and view all the answers

Which cell types are primarily involved in the humoral component of acquired immunity?

B-lymphocytes and plasma cells Signup and view all the answers

Which statement accurately describes a characteristic of acquired immunity?

It can recognize self and non-self. Signup and view all the answers

What role do IgG antibodies play in natural passive immunity?

They provide temporary immunity from the mother to the fetus. Signup and view all the answers

What mechanism distinguishes artificial passive immunity from natural passive immunity?

It involves injecting preformed antibodies into the host. Signup and view all the answers

What is the role of plasma cells in the immune response?

They produce soluble antibodies. Signup and view all the answers

Which process allows for the generation of a diverse population of antibodies?

Random combinations of gene segments and mutations. Signup and view all the answers

Which type of antibody is primarily found in mucosal areas and serves to prevent pathogen colonization?

IgA Signup and view all the answers

What is unique about the hyper variable region of an antibody?

It leads to the antibody's diversity in antigen recognition. Signup and view all the answers

What is class switching in the context of antibody production?

Changing the isotype of the antibody while retaining the variable region. Signup and view all the answers

Which statement is true regarding early endogenous antibody production?

It generally appears within the first years of life. Signup and view all the answers

What mechanism allows antibodies to function effectively in the humoral immune system?

Their presence in the bloodstream. Signup and view all the answers

What does opsonization refer to in the context of antibodies?

The coating of pathogens to enhance phagocytosis. Signup and view all the answers

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

Phagocytizing bacteria and fungi Signup and view all the answers

What unique function is associated with eosinophils?

Killing bacteria and multicellular parasites Signup and view all the answers

Which statement about basophils is true?

They are involved in allergic responses by releasing histamine. Signup and view all the answers

Natural Killer (NK) cells function primarily by:

Killing infected host cells to prevent pathogen spread. Signup and view all the answers

Where are dendritic cells primarily located?

In tissues that contact external environments Signup and view all the answers

How are eosinophils activated to release their toxic proteins?

Activation is strictly controlled to minimize tissue damage. Signup and view all the answers

Which of the following best describes the role of dendritic cells in immune response?

They facilitate the transition between innate and adaptive immunity. Signup and view all the answers

What distinguishes neutrophils from other types of white blood cells?

They are the most abundant white blood cells. Signup and view all the answers

Which antibody is responsible for providing passive immunity to the fetus?

IgG Signup and view all the answers

What is the primary role of IgE antibodies?

To protect against parasitic worms and trigger histamine release Signup and view all the answers

Which antibody is expressed on the surface of B cells in a monomer form?

IgD Signup and view all the answers

Which antibody isotypes are expressed by a mature naive B lymphocyte?

IgM and IgD Signup and view all the answers

What triggers the differentiation of a B cell into a plasma cell?

Engagement with a cell-bound antibody molecule Signup and view all the answers

What is the significance of the suffixes in antibody isotypes like IgA, IgG, etc.?

They represent the different heavy chain types Signup and view all the answers

Which is the correct statement about IgM antibodies?

IgM eliminates pathogens in the early stages of B cell-mediated immunity. Signup and view all the answers

What is the primary function of the Fab region of an antibody?

To recognize specific foreign objects Signup and view all the answers

Which of the following is NOT a class of antibody isotype found in placental mammals?

IgH Signup and view all the answers

Which of the following describes the Fc region of an antibody?

It ensures appropriate immune response by binding to immune molecules. Signup and view all the answers

How do the heavy chain classes influence antibody isotypes?

They correspond to specific antibody isotypes. Signup and view all the answers

What are CDRs in the context of antibodies?

They are idiotypes involved in antigen binding. Signup and view all the answers

What role does the base of the Y shape of antibodies play?

It modulates immune cell activity. Signup and view all the answers

Which statement about light chains in mammals is true?

Light chains consist of one constant domain and one variable domain. Signup and view all the answers

What best describes the relationship between the Fab and Fc regions?

Fab regions mediate effects directed at immune cells while Fc regions direct them at microbes. Signup and view all the answers

What characterizes the constant region of an antibody?

It is identical in all antibodies of the same isotype. Signup and view all the answers

Study Notes

Immunology - Lecture 1

Immunology is the science of studying the body's defenses against pathogens, but also cancer.
Basic immunology examines the functions of immune cells and chemicals, and how they react to various functions.
Innate immunity protects against all intruders (pathogens). Innate immune cells include neutrophils, monocytes, macrophages, dendritic cells, natural killer cells, basophils, eosinophils, and others.
Adaptive immunity targets specific pathogens. Adaptive immune cells include B lymphocytes (responsible for antibody production, or humoral immunity) and T lymphocytes (responsible for cellular immunity).

Immunity and Its Types

Immunity is the state of resistance or susceptibility to diseases caused by microorganisms or their toxic products.
Immunity can be innate or acquired (adaptive).
Innate immunity is present at birth, while acquired immunity develops later in life.
Innate immunity is broadly categorized into Natural (passive, active) and Artificial (passive, active) immunity.
Acquired immunity can be active (infection or immunization) or passive (maternal or antibody transfer).

Innate or Natural Immunity

Innate immunity acts as the body's first line of defense against microorganisms.
Components include cellular (mast cells, neutrophils, macrophages) and humoral (complement, lysozyme, interferon) components.
Mechanisms include anatomical barriers (skin, mucus membranes), physiological conditions (body temperature, pH), and chemical barriers (lysozyme in tears, acidic pH in stomach).
Skin provides a physical barrier, with epidermis (outer layer) and dermis (inner layer). Epidermis contains dead cells filled with keratin, while dermis contains connective tissue, hair follicles, and glands.
Mucus membranes also trap microbes.
High salt concentration in sweat, lysozyme, and acidity in the stomach are antimicrobial agents.

Types of Innate Immunity

Species immunity: certain species are resistant to diseases others are susceptible to, like mammals with anthrax.
Racial immunity: certain races may show resistance to specific diseases, but this could be due to socioeconomics, habitat, culture, etc.
Individual immunity: health status, nutrition, previous illnesses, hygiene, and genetic factors affect individual susceptibility to certain diseases.

Cells of the Innate Immune System - Lecture 2

Leukocytes (white blood cells) patrol the body in the circulatory system to defend against threats.
Phagocytes are "eating cells" that engulf and destroy bacteria and viruses.
Phagocytosis involves several steps: approach to infection site, adherence of antigen, engulfment to phagosome, fusion to form phagolysosome, killing and digestion of pathogen, release of debris.
Phagocytes include neutrophils, macrophages, and dendritic cells.
Neutrophils are often a first responder to sites of infection, with the bone marrow producing 100 billion new neutrophils per day.
Macrophages can leave the circulatory system and roam the body to fight infection. They release cytokines.
Mast cells are important in the inflammatory response and release mediators.

Third Line of Defense: Acquired or Adaptive Immunity - Lecture 5

Acquired immunity develops later in life in response to microbial infections.
Components include antibodies and lymphocytes like B and T cells.
Characteristics include specificity, self-non-self recognition, immunological memory and diversity.
Types of acquired immunity: active and passive.
Active immunity: produced by the host (infection or vaccination).
Passive immunity: produced in another host and transferred to the recipient or passively acquired (maternally, ex. from placenta).

Adaptive Immune Cells - Lecture 5, 10

Lymphocytes (B and T cells) are central to adaptive immunity.
B cells mature in the bone marrow and are involved in antibody production.
T cells mature in the thymus and are vital for cellular immunity responses and antibody regulation.

Types of T Cells - Lecture 6

CD4+ T cells (helper T cells): recognize non-peptide-binding region of MHC class II molecules, and are crucial in regulating other immune cells; some are regulatory T (Tregs) which maintain tolerance.
CD8+ T cells (cytotoxic T cells): recognize non-peptide-binding region of MHC class I molecules; are important in destroying cells infected by intracellular microbes.

B Cells and Plasma Cells - Lecture 6

B cells are lymphocytic cells that differentiate into plasma cells, which produce and secrete antibodies.
B cells have a unique antigen receptor on their surfaces, critical for recognizing specific antigens, called B-cell receptors (BCRs)/immunoglobulins.

Natural Killer Cells - Lecture 6, 13

NK cells are important in destroying virally infected cells and tumor cells without prior sensitization.

Antigens - Lecture 6, 7, 15, 16

Antigens are substances that stimulate an immune response.
Immunogens are agents capable of inducing an immune response. (all immunogens are antigens, but not all antigens are immunogens).
Hapten: a small foreign molecule that is not antigenic unless conjugated with an antigenic molecule.

Types of Antigens

Exogenous antigens (encountered by host outside) are taken up by antigen-presenting cells (APCs) through phagocytosis and are displayed to other cells.
Endogenous antigens (manufactured inside the cell) are displayed through a different mechanism to alert the immune system.

Antibodies - Lecture 8

Antibodies are also called immunoglobulins (Igs).
Antibodies are Y-shaped glycoproteins, containing two identical heavy chains and two identical light chains, functioning to recognize and bind to antigens in a highly specific manner.
Different regions of the antibody have different functions; the Fab region recognizes the antigen (epitope) and the Fc region interacts with other parts of the immune system.
Antibodies can be classified into different isotypes (IgA, IgD, IgE, IgG, IgM). Each has distinct functions, locations and properties within the immune system.

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Description

Test your knowledge on key concepts of immunology, focusing on antibodies, their structures, and the humoral immune system. This quiz covers essential topics such as B cell receptors, immunoglobulin types, and the distinctions between acquired and innate immunity.