Summer Immuno Lecture 3 Flashcards

The immunoglobulin heavy-chain gene segments are found on which chromosome?

Each B-cell receptor is built from which chains?

A developing B cell has two copies of chromosome 14. How many heavy-chain loci are ultimately used?

A B-cell heavy-chain locus successfully makes a functional heavy chain. What is this called?
A. Class switching
B. Productive rearrangement
C. Affinity maturation
D. Somatic hypermutation

One chromosome 14 successfully rearranges first. What happens to the other chromosome 14 locus?
A. It class switches
B. It makes Igβ
C. It is silenced
D. It binds antigen

A mature B cell has completed receptor development. How many BCR specificities does it produce?
A. Two
B. One
C. Dozens
D. Hundreds

The antigen recognized by a B cell’s receptors is called its what?

_____ antigen

A BCR binds one small portion of a bacterial protein. What is that region called?
A. Isotype
B. Haplotype
C. Cognate antigen
D. Epitope

Which two accessory proteins transmit BCR signals inward?

Igα and Igβ are important because they help transmit signals to the what?
A. Lysosome
B. Thymus
C. Nucleus
D. Complement system

A soluble antigen binds only one BCR weakly. What event is usually needed for strong activation?
A. BCR crosslinking
B. C9 insertion
C. Fas binding
D. MHC loss

BCR crosslinking helps activation by clustering which molecules?
A. C3a and C5a
B. CD4 and CD8
C. Heavy and light chains
D. Igα and Igβ

Crosslinking can serve as a _____ so B cells are not activated all the time.

Besides BCRs, B cells also carry receptors for which immune system component?
A. Interferon
B. Complement
C. Perforin
D. Hemoglobin

A bacterial antigen is coated with complement fragments. Which B-cell receptor can bind those fragments?
A. Complement receptor
B. T-cell receptor
C. Fas receptor
D. Fc receptor

A B cell binds both an epitope and a complement fragment. What is the complement receptor called?

A B cell has never encountered its cognate antigen. What is it called?
A. Experienced B cell
B. Plasma B cell
C. Naive B cell
D. Memory B cell

Which term also describes a naive B cell?
A. Effector
B. Virgin
C. Experienced
D. Activated

A B cell has already encountered its cognate antigen. What is it called?
A. Virgin B cell
B. Immature B cell
C. Naive B cell
D. Experienced B cell

Most naive B cells require how many signals for activation?
A. Two
B. One
C. Three
D. Four

For naive B cells, in T-cell-dependent activation, what is signal 1?

____ ____

For naive B cells, in T-cell-dependent activation, which cell supplies signal 2?

____ ____ ____

The second signal for naive B-cell activation is also called what?
A. Co-stimulatory signal
B. Opsonizing signal
C. Apoptotic signal
D. Neutralizing signal

A naive B cell needs helper T-cell assistance for activation. What is this called?
A. Alternative activation
B. Lectin activation
C. T-cell-dependent activation
D. Complement activation

During T-cell-dependent activation, helper T cells use which surface molecule?
A. CD40
B. CD40L
C. Igα
D. Igβ

CD40L on helper T cells interacts with which B-cell molecule?
A. Igβ
B. ICAM
C. Fas
D. CD40

The CD40L-CD40 interaction provides which signal?
A. Signal 1
B. Co-stimulatory signal
C. Complement signal
D. Danger signal only

A polysaccharide antigen has many identical repeated epitopes. What can it strongly cause?
A. CD40 silencing
B. MHC I loss
C. BCR crosslinking
D. Igβ destruction

Repeated epitopes activate B cells without helper T cells. What is this called?
A. T-cell-independent activation
B. T-cell-dependent activation
C. Productive rearrangement
D. Somatic hypermutation

Even in T-cell-independent activation, what additional signal is still required?
A. CD40L signal
B. Thymic signal
C. Antibody signal
D. Danger signal

Which self molecule has repeated epitopes but should not normally activate B cells?
A. TNF
B. DNA
C. LPS
D. C3b

During heavy-chain selection, both chromosome 14 copies initially do what?
A. Rearrange gene segments
B. Secrete antibodies
C. Bind helper T cells
D. Express CD40L

The “winner” chromosome 14 is selected because it makes what first?

____ ____ ____

A mature B cell secretes antibodies matching its surface BCR. How many antibody types does it make?
A. Two unrelated types
B. One specific type
C. Many random types
D. Four chain types

BCR crosslinking is essential because one BCR alone usually gives what?
A. Excessive apoptosis
B. Strong complement activation
C. Immediate antibody secretion
D. Weak activation signaling

A B cell binds complement-coated antigen through its co-receptor. What happens to signaling?
A. It is amplified
B. It is blocked
C. It becomes unrelated
D. It causes silence

Why is the complement receptor considered a co-receptor?
A. It makes antibodies
B. It replaces BCRs
C. It strengthens signaling
D. It silences CD40

Which combination gives a stronger B-cell signal?
A. Complement binding alone
B. BCR plus complement receptor
C. CD40 alone
D. Igβ alone

Which antigen type is most likely to activate B cells without helper T-cell co-stimulation?
A. Single epitope protein
B. Small soluble peptide
C. Host DNA alone
D. Repetitive polysaccharide

T-cell-independent activation still needs a danger signal to prevent what?
A. Class switching
B. Random self-attack
C. Heavy-chain failure
D. Complement production

Why does DNA not normally trigger strong B-cell activation despite repeated epitopes?

____ signal is absent

Helper T cells recognize antigen mainly through which molecule?
A. Class I MHC
B. B-cell receptor
C. Complement receptor
D. Class II MHC

T-cell-independent activation helps adaptive immunity respond to _____ and _____

A parasite produces a molecule that activates many unrelated B cells. What is this molecule called?

_____

A mitogen activates B cells by binding molecules other than what?
A. BCRs
B. CD40
C. Complement
D. IgM

A parasite causes many nonspecific B cells to activate at once. What is this called?
A. Class switching
B. Affinity maturation
C. Complement fixation
D. Polyclonal activation

In polyclonal activation, BCRs become crosslinked by what mechanism?

Crosslinking by _____

Some parasites use polyclonal activation mainly to do what?

_____ _____ response

After activation and proliferation, B cells enter maturation with roughly how many possible steps?
A. One
B. Two
C. Three
D. Four

Which maturation step lets B cells change antibody class?
A. Somatic hypermutation
B. Class switching
C. Polyclonal activation
D. Complement fixation

Which maturation step can increase BCR affinity?
A. Class switching
B. ADCC
C. Complement fixation
D. Somatic hypermutation

Somatic hypermutation changes BCRs to improve binding to what?
A. Cognate antigen
B. Class II MHC
C. C1 inhibitor
D. Fc receptor

During the “career decision,” a B cell may become which antibody factory?
A. Memory B cell
B. Virgin B cell
C. Plasma B cell
D. Naive B cell

During maturation, a B cell may also become which long-lived cell?
A. Mitogen cell
B. Memory B cell
C. C1 complex
D. Helper T cell

The three maturation events must occur in what order?
A. Class switch first
B. Hypermutation first
C. No required order
D. Plasma decision first

Which statement about B-cell maturation steps is correct?
A. Not all must occur
B. All always occur
C. They need TLR4
D. IgM blocks them

When a virgin B cell is first activated, it mainly produces which antibody?

First-activated virgin B cells can also produce tiny amounts of which antibody?

The immune function of IgD is best described as what?

Class switching changes antibody production from IgM to which possible class?
A. IgM only
B. IgD only
C. IgG, IgE, or IgA
D. C1, C3, or C5

In class switching, which antibody region remains unchanged?
A. Fc region
B. Fab region
C. C1 region
D. Heavy constant only

In class switching, which antibody region changes?
A. Fab region
B. Epitope region
C. Antigen-binding region
D. Constant Fc region

After class switching, antigen specificity does what?
A. Stays the same
B. Becomes random
C. Recognizes MHC
D. Recognizes complement

After class switching, antibody function changes because the antibody gets what?
A. New Fab region
B. New Fc region
C. New epitope
D. New antigen

Which antibody is especially good at activating complement?

Activating complement by antibody is also called what?
A. Neutralizing complement
B. Opsonizing complement
C. Fixing complement
D. Silencing complement

In blood, about 30 complement proteins form which complex?

C1 complexes are normally bound by what?
A. Inhibitors
B. Antibodies
C. Fc receptors
D. Mitogens

What happens when two C1 complexes come close together?
A. They bind DNA
B. They become IgM
C. They cross placenta
D. Inhibitors fall off

C1 inhibitor release allows which process to begin?

____ ____

IgM must first bind what before efficiently activating C1?

_____

Antigen-bound IgM can bind multiple C1 complexes using what region?

____ region

Antigen-bound IgM brings C1 complexes together, triggering what?
A. Somatic hypermutation
B. Complement cascade
C. Class II display
D. IgD production

IgG can fix complement, but which antibody does it more efficiently?

Why is IgM especially efficient at fixing complement?
A. It crosses placenta
B. It has five Fc regions
C. It binds NK cells
D. It lacks Fab regions

Among IgG subclasses, which fixes the most complement?
A. IgG1
B. IgG2
C. IgG4
D. IgG3

Which IgG subclass is best at opsonizing invaders?
A. IgG1
B. IgG2
C. IgG3
D. IgG4

Besides complement fixation, IgG3 can help perform which process?
A. Somatic hypermutation
B. T-independent activation
C. Mitogen activation
D. Antibody-dependent cellular cytotoxicity

IgG3 ____ the target cell, and the NK cell binds the IgG3 Fc region through ____. This links the NK cell to the target and activates killing.

Which antibody class can transfer from mother to fetus?

Maternal IgG reaches the fetus from the mother’s what?

_____

Maternal IgG protects the infant until what happens?
A. Infant makes its own
B. IgM crosses placenta
C. C1 becomes active
D. IgD matures

IgG supplied from the mother protects infants for roughly how long?
A. Hours after birth
B. One day after birth
C. Several months after birth
D. Until adolescence

Another term for IgG antibodies is what?
A. Gamma globulins
B. Alpha globulins
C. Beta globulins
D. C1 globulins

After hepatitis A exposure, some patients receive what injection?
A. IgM vaccine
B. Complement inhibitor
C. Mitogen blocker
D. Gamma globulin

Gamma globulin injections contain antibodies from how many people?
A. Many donors
B. One donor
C. Fetal donors only
D. Parasite-infected donors

Why can pooled gamma globulin help after hepatitis A exposure?
A. It supplies mitogens
B. It kills B cells
C. Some donors have anti-HAV antibodies
D. It blocks class II MHC

The goal of gamma globulin after exposure is to help do what?
A. Neutralize the virus
B. Trigger polyclonal activation
C. Fix all complement
D. Block NK cells

Gamma globulin protection is meant to last until what occurs?
A. C1 disappears
B. IgD function clarifies
C. Own immune response develops
D. Mitogens leave blood

Polyclonal activation is dangerous because it activates B cells how?
A. Antigen-specific
B. Nonspecifically
C. Via its memory cells
D. Via its IgG cells

A patient receives pooled IgG after HAV exposure. What type of immunity is this?
A. Active adaptive
B. Innate cellular
C. Passive antibody-mediated
D. T-cell dependent

Which feature remains constant after class switching?
A. Antigen bound
B. Fc-mediated function
C. Antibody class
D. Complement ability

Which feature changes after class switching?
A. Cognate antigen
B. Epitope recognized
C. Fab specificity
D. Effector function

Which antibody is most abundant overall in the body?

Which antibody is most abundant in blood?

A patient has recurrent infections at mucosal surfaces. Which antibody class is most important there?

The “clip” structure of IgA helps transport IgA across which barrier?
A. Placental barrier
B. Intestinal wall
C. Blood-brain barrier
D. Splenic sinusoid

The IgA “clip” structure helps resist which threat?
A. Digestive acids and enzymes
B. Complement-mediated lysis
C. Mast-cell degranulation
D. T-cell apoptosis

A breastfeeding infant receives antibody protection coating the gut mucosa. Which antibody is provided?

Why is IgA poor at fixing complement?
A. IgA lacks Fab regions
B. C1 cannot bind IgA Fc
C. IgA destroys complement proteins
D. IgA blocks all cytokines

Anaphylactic shock is caused by _____ of _____ cells.

Mast-cell degranulation releases which major active chemical?
A. Histamine
B. Perforin
C. C3b
D. IFN-gamma

IgE is produced in response to what?
A. Self DNA
B. Allergens
C. C1 complexes
D. MHC I loss

Which cells carry IgE receptors involved in allergy?
A. Neutrophils
B. Plasma cells
C. Mast cells
D. Erythrocytes

IgE-bound mast cells dump granules into tissues. What is this process called?
A. Degranulation
B. Opsonization
C. Neutralization
D. Affinity maturation

Antibody class switching is controlled mainly by _____ encountered by activated _____ cells.

Examples of cytokines encoutered and class switching:

IL-4, IL-5 → ____ subclasses
IFN-γ → opsonizing ____ subclasses
TGF-β → ____

IL-4 and IL-5 are abundant in ____ reactions and ____ infections.

Very high mutation rates occur in selected B-cell gene regions. What is this called?
A. Somatic hypermutation
B. Class switching
C. Polyclonal activation
D. Complement fixation

Somatic hypermutation especially affects regions containing which segments?
A. C only
B. V, D, J
C. Fc and C2
D. C1 and V

Somatic hypermutation occurs after which event?
A. Mast-cell priming
B. VDJ selection
C. IgA secretion
D. Complement fixation

Somatic hypermutation occurs after which rearrangement is selected?
A. Productive rearrangement
B. Polyclonal rearrangement
C. Fc rearrangement
D. Complement rearrangement

Somatic hypermutation can affect BCR affinity in which way?
A. Increase only
B. Decrease only
C. Increase, decrease, or unchanged
D. Always unchanged

B cells with higher-affinity BCRs compete better for what?
A. T-cell help
B. C1 inhibitor
C. Mast-cell granules
D. Intestinal transport

During affinity selection, T-cell help is best described as what?
A. Unlimited
B. Irrelevant
C. Limited
D. Toxic

The end result of somatic hypermutation is BCRs that bind antigen how?
A. Weakly
B. Tightly
C. Randomly
D. Nonspecifically

Fine-tuning BCRs toward higher average affinity is called what?
A. Class switching
B. Polyclonal activation
C. Complement fixation
D. Affinity maturation

T-cell-independent B-cell activation usually lacks which processes?

____ ____ and ____ ____

B cells activated independently of T cells do not produce which cells?

____ B cells

In T-cell-independent activation, activated B cells become what?

____ B cells

Maternal milk IgA mainly protects against pathogens entering through what route?
A. Respiratory inhalation
B. Placental circulation
C. Skin abrasions
D. Ingestion

The alternative complement pathway is _____

The classical complement pathway is _____

The longest lived antibody class is ____

Which antibody is the least abundant in the body?

A pathogen is coated with complement fragments. Which B-cell mechanism helps recognize this opsonized invader?

A. B-cell coreceptors

B. T-cell receptor rearrangement

C. NK-cell CD16 binding

D. Mast cell degranulation

Direct binding of antigen to which receptor can signal a B cell?

A. CD8

B. BCR

C. MHC I

D. FcεRI

T-cell independent B-cell activation first starts with which event?

A. Class switching before antigen binding

B. Cytokine release by Th2 cells

C. Plasma cell apoptosis

D. Crosslinking of BCRs

A bacterial polysaccharide antigen binds and crosslinks multiple BCRs on a B cell. What type of activation can this initiate?

A. T-cell independent B-cell activation

B. CD8 T-cell activation

C. NK-cell licensing

D. IgE-mediated mast cell activation

After BCR crosslinking, T-cell independent B-cell activation also requires what?

A. MHC I downregulation

B. A naive helper T cell

C. An active bacterial invader or danger signal

D. Eosinophil activation

T-cell independent B-cell activation is best described as which type of process?

A. Antigen nonspecific

B. Antigen specific

C. MHC I restricted

D. NK-cell dependent

Most B cells activated without T-cell help are found in which organ

A. Thymus

B. Bone marrow

C. Lymph node cortex

D. Spleen

A splenectomized patient is especially vulnerable to encapsulated bacteria. Which organism is a classic example?

A. *Streptococcus pneumoniae*

B. *Candida albicans*

C. *Histoplasma capsulatum*

D. *Trichophyton rubrum*