Microbio Exam 4: Chapter 17 Adaptive Immunity

defenses that target a specific pathogen after exposure

adaptive immunity

What is the ability of the immune system to distinguish 'self' from 'nonself'?

Adaptive immunity

When is the adaptive immune system activated?

When innate defenses fail to stop a microbe

How is adaptive immunity acquired?

Through infection or vaccination

What is the primary response in the adaptive immune system?

The first time the immune system combats a particular foreign substance

What is the secondary response in the adaptive immune system?

Later interactions with the same foreign substance; faster and more effective due to 'memory'

What type of immunity involves the production of antibodies?

Humoral immunity

What are antibodies combatting foreign molecules known as?

Antigens

Where are B cells created and matured?

In red bone marrow

What do B cells do when they recognize antigens?

They make antibodies

What are B cells named after?

The bursa of Fabricius in birds

Where do mature B cells reside?

In the blood and lymphoid organs

What types of substances can antigens be?

Proteins, lipids, carbohydrates, DNA, or RNA

What does humoral immunity describe?

Immune actions taking place in extracellular fluids, brought about by antibodies

What are B cell receptors (BCRs)?

Membrane immunoglobulins specific for a particular antigen

What happens when a B cell binds to an antigen?

The B cell is activated to secrete thousands of immunoglobulins

Where are both B and T lymphocytes initially produced?

In the fetal liver

Where do B lymphocytes mature?

In red bone marrow

What is cellular immunity also known as?

Cell-mediated immunity

What type of lymphocytes are involved in cellular immunity?

T lymphocytes

Where do T lymphocytes mature?

In the thymus

Where do T lymphocytes reside?

In blood and lymphoid organs

What do T cell receptors (TCRs) recognize?

Antigenic peptides processed by phagocytic cells

What do T cell receptors (TCRs) do instead of binding to free-floating antigens?

They recognize antigenic peptides presented by specialized molecules on body cells.

What type of pathogens are T lymphocytes best at fighting?

Virus-infected cells and intracellular bacteria

What do T lymphocytes respond directly to?

Viruses, chlamydia, and rickettsia

What role do T helper cells play in the immune response?

They help B cells produce antibodies.

What is the function of T suppressor cells?

They help regulate the immune response.

What do T cytotoxic cells do?

They directly kill infected cells.

What do delayed hypersensitivity T cells assist with?

They help macrophages find abhorrent cells.

What type of cells are antigen-presenting cells?

Dendritic cells and macrophages

What type of immunity attacks antigens that have already entered cells?

Cellular immunity

Which pathogens are targeted by cellular immunity?

Viruses and some intracellular bacteria such as M. leprae and L. monocytogenes

How does cellular immunity make contact with infected cells?

It makes direct contact with that cell.

What type of immunity fights invaders and threats outside cells?

Humoral immunity

What types of threats does humoral immunity target?

Extracellular bacteria and toxins, and viruses before they enter a host cell

How do B cells respond to infected cells?

They release an antibody that responds to the infected cells.

What are cytokines?

Cytokines are chemical messengers produced in response to a stimulus.

What types of cells produce cytokines?

Nearly all types of activated immune cells produce cytokines.

What is the function of cytokines?

Cytokines activate nearby immune cells bearing the corresponding cytokine receptors.

What are interleukins (ILs)?

Interleukins are cytokines that facilitate communication between leukocytes.

What do interleukins do?

Interleukins stimulate cell proliferation, maturation, migration, or activation during an immune response.

What are chemokines?

Chemokines are cytokines that induce migration of leukocytes to areas of infection or tissue damage.

What is the role of chemokines in the immune response?

Chemokines attract cells to the site of infection.

What are interferons (IFNs)?

Interferons are cytokines that interfere with viral infections of host cells.

What is the function of interferons?

Interferons help protect neighboring cells from viral infections.

What is tumor necrosis factor alpha (TNF-α)?

TNF-α is a cytokine involved in the inflammatory reactions of autoimmune diseases.

What are hematopoietic cytokines?

Hematopoietic cytokines control stem cells that develop into red and white blood cells.

What can overproduction of cytokines lead to?

Overproduction of cytokines can lead to a cytokine storm.

What are antigens?

Substances that induce the production of antibodies.

What are common components of antigens?

Capsules, cell walls, flagella, fimbriae, toxins, viral capsids, viral spikes.

What are nonmicrobial antigens?

Examples include egg white, pollen, and cell surface molecules.

What are epitopes?

Specific regions on antigens that antibodies interact with.

What is a monoclonal antibody?

An antibody that is derived from a single clone of B cells.

What are haptens?

Molecules too small to be antigenic that attach to carrier molecules and provoke an immune response.

What happens once an antibody against a hapten is formed?

The antibody will react with the hapten independent of the carrier molecule.

What are antibodies?

Compact soluble proteins called immunoglobulins (Ig)

What do antibodies recognize and bind to?

Specific antigens, targeting them for destruction

What is valence in relation to antibodies?

The number of antigen-binding sites on an antibody

What are bivalent antibodies?

Antibodies that have two binding sites

How many identical antigen-binding sites does each antibody have?

At least two identical antigen-binding sites that bind to identical epitopes

Why is a bivalent antibody called a monomer?

Because it has the simplest molecular structure

What is the structure of an antibody monomer?

Four protein chains that form a Y-shape

What types of chains make up an antibody monomer?

Two identical light chains and two identical heavy chains joined by disulfide links

Where are the variable (v) regions located on an antibody?

At the ends of the arms

What forms the antigen-binding site on an antibody?

The very tip of each arm

What is the constant (Fc) region of an antibody?

The stem (the lower parts of the arms) that is identical for a particular Ig class

How many classes of immunoglobulins (Ig) are there?

Five classes (IgG, IgM, IgA, IgD, IgE)

Which immunoglobulin molecules are secreted as monomers?

IgG, IgD, and IgE

How is IgA secreted?

Either as a monomer or as a dimer (two molecules linked together)

How is IgM secreted?

As a pentameric ring, with five antibodies linked together

What is the structure of IgG?

Monomer

What percentage of serum antibodies does IgG constitute?

80%

Where is IgG found in the body?

In the blood, lymph, and intestine

What is one action of IgG?

Cross the placenta and protect the fetus

What is another action of IgG?

Trigger complement activation

What is a third action of IgG?

Enhance phagocytosis

What is a fourth action of IgG?

Neutralize toxins and viruses

What is the structure of IgM?

Pentamer made of five monomers held with a J chain

What is the valence of IgM?

10

What percentage of serum antibodies does IgM constitute?

6%

Where does IgM remain in the body?

In blood vessels

What is one function of IgM?

Causes agglutination (clumping) of cells and viruses

What is another function of IgM?

Activates complement

When is IgM released?

As a first response to an infection; short lived

What class of antibody is involved in the response to ABO blood group antigens?

IgM

What is the structure of IgA in serum?

Monomer

What is the structure of IgA in secretions?

Dimer

What percentage of serum antibodies does IgA constitute?

13%

Where is IgA commonly found?

In mucous membranes, saliva, tears, and breast milk

What is the function of IgA?

Prevent microbial attachment to mucous membranes

What is the structure of IgD?

Monomer

What percentage of serum antibodies does IgD constitute?

0.02%

What is the structure similarity of IgD to another antibody?

Similar to IgG

Where is IgD found?

In blood, in lymph, and on B cells

What is the well-defined function of IgD in serum?

No well-defined function

What potential role does IgD play?

May play a role as a membrane immunoglobulin on B cells

What is the structure of IgE?

Monomer

What percentage of serum antibodies does IgE constitute?

0.002%

Where is IgE found?

On mast cells, on basophils, and in blood