VMED 5172 / Clinical Immunology - Antibodies and Receptor Diversity

Four

Antibody molecules have how many polypeptide chains?

Antigen binding

What process occurs at the variable domain of an antibody?

Carries out the function of antibodies including microbial neutralization and opsonization

What purpose do constant domains serve in antibodies?

Hinge region

Which region of an antibody provides flexibility?

One, two

Humans have ___ heavy and ___ light chains

True

True or False: Both light chains on an antibody must be of the same class

Kappa or Lambda

Which type of light chains may be found on an Ig chain?

Constant domain

Which portion of the antibody is species specific?

IgG

In which immunoglobulins is a hinge region found?

Heavy chain

Which portion of the antibody determines its isotype?

IgM

Which immunoglobulin class has a mu (μ) heavy chain?

IgY

Which immunoglobulin type is specific to birds and reptiles?

False

True or False: All animals have two light chains

Combinatorial diversity of V-D-J joining, junctional diversity, combinatorial diversity of pairing, and somatic hypermutation

Individuals can produce up to 5 x 10^13 different B cell receptors due to which processes?

Somatic recombination; generation of different heavy and light chains

In which process are V, D, and J segments selected in a random manner? This generates what?

Each possible combination of V, D, and J segments along with added nucleotides yields an antibody which can recognize a specific antigen

How is combinatorial diversity defined?

Nucleotides

Junctional diversity includes the addition of ____ to selected DNA segments

After B cell activation

When does somatic hypermutation occur?

Increases antibody diversity to improve affinity for antigen

What does somatic hypermutation achieve?

Mutations initiated by AID introduce changes in amino acids of the variable region

How is affinity improved in somatic hypermutation?

D segment

Light chains do not contain which locus?

IgM, IgD, IgG, IgA, IgE

What is the 'order' of antibody isotypes in terms of class switching?

False (Class switching cannot occur backwards)

True or False: A B cell which was previously producing IgA can begin producing IgG

IgM and IgE; extra heavy chain domain

Which immunoglobulin isotypes lack a hinge region? What do they have instead?

Number and location of disulfide bonds, and distribution of linked sugar molecules

Other than differences in heavy chains and hinge regions, what other differences are present in different isotypes?

Neutralization, opsonization, antibody dependent cell-mediated cytotoxicity, lysis of microbes or abnormal cells, and activation of other effector cells

What are the major functions of antibodies?

IgM

The first antibody produced during the primary response is?

Great at complement activation

What major function does IgM have?

5; it is very large and cannot enter into or reach deep into tissue

IgM has ___ subunits. Why is this an issue?

In the blood

Where is IgG seen in its highest concentrations?

IgG

Which Ig isotypes are seen in high concentrations during secondary exposures?

They are the smallest of the isotypes

IgG isotypes have good mobility into tissue. Why is this?

Neonatal

In some species, IgG may be involved in ___ immunity due to its good tissue mobility

Plasma cells, in mucosal tissue

IgA is secreted by which cells? Where does this occur?

Joining chain and secretory component; protect against digestion

What two parts are unique to an IgA molecule, and what are they used for?

Dimer; monomer

IgA is secreted as a ___, but may circulate in the blood as a ___

Critical for mucosal immunity

What is the major function of IgA?

IgE

Which immunoglobulin isotype is present in low concentrations in serum?

Most IgE is already bound to receptors on mast cells and basophils

Why does IgE tend to be found in lower concentrations?

Immunity to parasites and type I hypersensitivity/allergies

IgE is involved in which processes?

Bind one epitope, or fragment of an antigen

Fab regions of an antibody give them the ability to?

Fragment crystallizable (Fc) region

Which portion of the antibody is responsible for activating the complement?

Phagocytes, eosinophils, NK cells, and mast cells

Which major cells have FcR?

Isotype

FC receptors are ____ specific

Mediate phagocytosis of microbes, drives cell-mediated cytotoxicity, and triggers mast cell degranulation

What are the major functions of Fc receptors?

Fc-gamma-RIIB

Inhibition of B cells includes which receptor?

Antigen-antibody complexes bind to Fc-gamma receptors

What signal causes B cells to be inhibited?

B

Which of the following statement is not true?

A. IgA Defense at mucosal sites

B. IgD Function in cell-mediated cytotoxicity

C. IgE Defense against parasites and involved in allergic diseases

D. IgM First one produced after B-cell activation

D

Which of the following is the most abundant

immunoglobulin class in healthy adult humans and mice?

A. IgA

B. IgM

C. IgE

D. IgG

D

Which of the following is not an antibody effector function?

A. Opsonization

B. Neutralization

C. Complement activation

D. Endogenous antigen presentation

C

Somatic hypermutation of Ig genes accounts for:

A. Allelic exclusion

B. Class switching from IgM to IgG

C. Affinity maturation

D. DNA recombination

A

The basic Ig unit is composed of:

A. 2 identical heavy and 2 identical light chains

B. 2 identical heavy and 2 different light chains

C. 2 different heavy and 2 identical light chains

D. 2 different heavy and 2 different light chains

B

Which of the following gene clusters do not contribute to

antigen binding:

A. Variable domain of light chain

B. Constant domain of heavy chain

C. Diversity segments (D)

D. Joining segments (J)

A

Which of the following statements does not apply to IgG?

A. Appears early in the primary immune response

B. Neutralizes bacterial toxins

C. Can fix complement

D. Crosses the human placenta

B

The Fab region of an Ig is responsible for:

A. C1q fixation

B. Binding to antigen

C. Binding to Fc receptors

D. Binding to macrophages

C

Somatic hypermutation is:

A. Commonly found in both Ig and T-cell receptor genes

B. Restricted to the constant region

C. Restricted to the variable region

D. Found only in Ig heavy chains

B

B lymphocytes in the lamina propria secrete large amounts of:

A. IgD

B. IgA

C. IgM

D. Bile acids

A

High affinity B-cell clones in mammals are usually

generated by:

A. Somatic hypermutation

B. Somatic DNA recombination

C. Pairing light and heavy chains

D. Class switching

C

Prior to class switching, B-cells express:

A. IgA alone

B. IgA and IgG

C. IgM and IgD

D. IgD alone

B

Toxins are neutralized by:

A. Complement

B. Antibody

C. Antimicrobial peptides

D. Lipid inflammatory mediator like PGE2