Biomed 2

Specialized epithelial M cells in Peyer’s patches function to: a) Capture antigens and transport them to dendritic cells; b) Directly kill microbes; c) Produce antibodies; d) Activate NK cells

a) Capture antigens and transport them to dendritic cells

Which of the following is NOT a secondary lymphoid tissue? a) Lymph nodes; b) Spleen; c) Thymus; d) MALT

c) Thymus

Complements are best described as: a) Plasma proteins activated by proteolytic cleavage in defense against microbes; b) Hormones regulating immune memory; c) Enzymes that digest antibodies; d) Cell-surface receptors for antigens

a) Plasma proteins activated by proteolytic cleavage in defense against microbes

Complement activation occurs through: a) Gene transcription; b) Proteolytic cleavage; c) Mitochondrial metabolism; d) Antibody degradation

b) Proteolytic cleavage

Complements help phagocytes kill microbes by: a) Marking microbes with C3b; b) Forming the MAC; c) Recruiting phagocytes (C3a); d) Inhibiting antigen presentation in lymph nodes

a) Marking microbes with C3b

Complement serves as an opsonin by: a) Enhancing phagocytosis; b) Blocking T-cell activation; c) Destroying antibodies; d) Reducing inflammation

a) Enhancing phagocytosis

Opsonization and phagocytosis in the complement system are primarily mediated by: a) C3a; b) C3b; c) C5a; d) C9

b) C3b

Deposition of C3b on bacterial surfaces results in: a) Prevention of phagocytosis; b) CR1-mediated binding to macrophages and phagolysosome formation; c) Antibody destruction; d) Viral replication

b) CR1-mediated binding to macrophages and phagolysosome formation

All of the following are major outcomes of complement activation EXCEPT: a) Opsonization of microbes via C3b; b) Formation of the MAC for membrane perforation; c) Recruitment of inflammatory cells; d) Increased antibody gene transcription

d) Increased antibody gene transcription

The primary function of the C3b molecule in the complement system is: a) Inhibition of inflammation; b) Activation of natural killer cells; c) Opsonization of pathogens; d) Inhibition of antibody production

c) Opsonization of pathogens

In the innate immune response, pathogens are recognized by: a) Random receptors; b) Pattern recognition receptors (PRRs) with limited repertoires; c) T-cell receptors; d) B-cell receptors

b) Pattern recognition receptors (PRRs) with limited repertoires

PRRs recognize: a) Human cell membrane proteins; b) Food antigens; c) Microbial signature structures known as PAMPs; d) Only viral DNA

c) Microbial signature structures known as PAMPs

PRRs do NOT recognize: a) Host cells; b) Fungi; c) Bacteria; d) Viruses

a) Host cells

PRRs require prior exposure to pathogens before activation: a) True; b) False

b) False

Binding of PAMPs to PRRs results in: a) Inhibition of inflammatory cytokines; b) Activation of phagocytosis and inflammatory cytokine secretion; c) Suppression of adaptive immunity; d) Destruction of MHC molecules

b) Activation of phagocytosis and inflammatory cytokine secretion

PAMP-PRR interaction activates dendritic cells by inducing: a) Rapid cell death; b) Maturation into antigen-presenting cells; c) Loss of MHC expression; d) Inhibition of migration

b) Maturation into antigen-presenting cells

The first cells to encounter pathogens in most infections are: a) B cells; b) T cells; c) Neutrophils and macrophages; d) NK cells

c) Neutrophils and macrophages

Which cells can directly phagocytose pathogens? a) Macrophages and neutrophils; b) B cells and T cells; c) NK cells only; d) Eosinophils only

a) Macrophages and neutrophils

After capturing antigens at infection sites, dendritic cells: a) Die immediately; b) Remain at the infection site; c) Migrate to draining lymph nodes as mature APCs; d) Differentiate into neutrophils

c) Migrate to draining lymph nodes as mature APCs

In adaptive immunity, dendritic cells present antigens using MHC molecules to: a) Activate macrophages; b) Stimulate naïve T cells into Th and Tc cells; c) Stimulate NK cells; d) Destroy B cells

b) Stimulate naïve T cells into Th and Tc cells

After activation, Th and Tc cells leave the lymph node through the: a) Afferent lymphatics; b) Efferent lymphatics; c) Venous sinuses; d) Splenic artery

b) Efferent lymphatics

Th cells help B cells by: a) Killing them; b) Turning them into NK cells; c) Stimulating differentiation into plasma cells that secrete antibodies; d) Producing complement proteins

c) Stimulating differentiation into plasma cells that secrete antibodies

Antigen-presenting cells include all of the following EXCEPT: a) Dendritic cells; b) Macrophages; c) B cells; d) Neutrophils

d) Neutrophils

Dendritic cells recognize microbial patterns using: a) MHC molecules; b) PAMP receptors (PRRs); c) Antibodies; d) NK receptors

b) PAMP receptors (PRRs)

Upon activation, dendritic cells undergo: a) Maturation into APCs; b) Cell shrinkage; c) Antibody secretion; d) Cell lysis

a) Maturation into APCs

During maturation, dendritic cells upregulate all EXCEPT: a) MHC molecules; b) B7/CD80/CD86 co-stimulatory molecules; c) CCR7 chemokine receptor; d) Complement proteins

d) Complement proteins

Which of the following is NOT an antigen-presenting cell? a) Dendritic cell; b) NK cell; c) B cell; d) Macrophage

b) NK cell

CD4 binds to ____ on APCs, while CD8 binds to ____ on nucleated cells: a) MHC I ; MHC II; b) MHC II ; MHC I; c) MHC III ; MHC I; d) MHC II ; MHC III

b) MHC II ; MHC I

Activation of naïve CD4 T cells requires: a) Only a cytokine signal; b) Only MHC binding; c) Both signal 1 and signal 2; d) Only co-stimulation

c) Both signal 1 and signal 2

Signal 1 and signal 2 for naïve CD4 T cells are: a) TCR–MHC II + CD28–B7; b) BCR–antigen + CD40–CD40L; c) TCR–MHC I + IL-2; d) CD28–IL-6 + TCR–antibody

a) TCR–MHC II + CD28–B7

T-cell activation induces: a) Clonal expansion of antigen-specific T cells; b) Immediate apoptosis; c) Antibody secretion; d) NK cell formation

a) Clonal expansion of antigen-specific T cells

If a T cell receives signal 1 without signal 2, it enters: a) Necrosis; b) Anergic state; c) Hyperactivation; d) Memory formation

b) Anergic state

Failed anergy mechanisms result in: a) Tissue repair; b) Autoimmune diseases; c) Immunodeficiency; d) Increased allergy tolerance

b) Autoimmune diseases

Signal 3 in T-cell activation is provided by: a) TCR only; b) Co-stimulatory molecules; c) Cytokines secreted by APCs; d) Antibodies

c) Cytokines secreted by APCs

IL-12 → Th1 cells that: a) Activate macrophages against intracellular pathogens; b) Activate eosinophils against parasites; c) Recruit neutrophils against fungi; d) Suppress immune response

a) Activate macrophages against intracellular pathogens

IL-4 → Th2 cells that: a) Activate macrophages; b) Activate eosinophils & B cells against parasites & allergy; c) Recruit neutrophils; d) Suppress immune response

b) Activate eosinophils & B cells against parasites & allergy

IL-6 and TGF-β → favor differentiation into: a) Th1; b) Th2; c) Th17 (recruit neutrophils vs fungi); d) Tc

c) Th17 (recruit neutrophils vs fungi)

IL-2 and TGF-β → favor development of: a) Th1; b) Th2; c) Th17; d) Treg

d) Treg

Which class of MHC molecules on APC presents antigens to CD4+ T cells? a) MHC class I; b) MHC class II; c) MHC class III; d) MHC class IV

b) MHC class II

Failure of anergy mechanisms is associated with: a) Tolerance to antigens; b) Chronic viral infection; c) Autoimmune diseases; d) Memory T cell formation

c) Autoimmune diseases