Immunology B Cell Activation Quiz
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Questions and Answers

Which type of antigens can activate B cells independently of THelper cell function?

  • Thymus-dependent antigens
  • Thymus-independent antigens (correct)
  • T-cell dependent antigens
  • Antigen presenting cells

What is the main function of TI-1 antigens?

  • Stimulate antibody affinity maturation
  • Induce clonal expansion of T cells
  • Cause polyclonal activation of B cells (correct)
  • Activate only mature B cells

What is the role of the B cell co-receptor complex?

  • Present antigens to T cells
  • Produce cytokines for T cell activation
  • Directly process antigens for MHC presentation
  • Enhance receptor signaling and activation (correct)

Which antigen class consists of highly repetitive structures that activate B cells by cross-linking BCRs?

<p>TI-2 antigens (B)</p> Signup and view all the answers

What is primarily produced by B cells activated through thymus-independent antigens?

<p>Low-affinity IgM antibodies (B)</p> Signup and view all the answers

What key role does CD21 play in B cell activation?

<p>Facilitates binding of BCR to pathogens (A)</p> Signup and view all the answers

Which group of B cells predominantly responds to thymus-independent antigens?

<p>Marginal zone B cells (A)</p> Signup and view all the answers

What is the primary function of CD40 activation on B cells?

<p>Promotes B cell survival through NFκB activation (C)</p> Signup and view all the answers

Which of the following cytokines is NOT mentioned as a signal provided by TFH cells to activate B cells?

<p>IL-10 (C)</p> Signup and view all the answers

What role do macrophages in the subcapsular sinus (SCS) of lymph nodes play?

<p>They express complement receptors to capture antigens (A)</p> Signup and view all the answers

What type of cells do centroblasts differentiate into within the germinal centre?

<p>Centrocytes (C)</p> Signup and view all the answers

Where are primary foci of activated B cells primarily located?

<p>In the medullary cords of the lymph node (D)</p> Signup and view all the answers

What characterizes plasma cells in terms of their lifespan and function?

<p>Long-lived and migrate to bone marrow for continued antibody production (C)</p> Signup and view all the answers

What is the role of TFH cells in the formation of germinal centres?

<p>They participate with B cells to sustain and enhance B cell proliferation (C)</p> Signup and view all the answers

What migratory change occurs in activated B cells after receiving T cell help?

<p>They downregulate CCR7 and move away from the T cell zone (B)</p> Signup and view all the answers

What is the defining structural component of a germinal centre?

<p>A mantle zone, light zone, and dark zone (C)</p> Signup and view all the answers

What type of antigens activate B cells through polyclonal activation without requiring THelper cell function?

<p>Thymus-independent antigens (A)</p> Signup and view all the answers

Which mechanism is involved in the activation of B cells by TI-2 antigens?

<p>Cross-linking of B cell receptors (C)</p> Signup and view all the answers

What is a characteristic feature of TI-1 antigens in relation to B cell activation?

<p>They cause proliferation of both immature and mature B cells (C)</p> Signup and view all the answers

Which statement accurately describes the role of CD19 in B cell activation?

<p>It amplifies the signal after BCR phosphorylation (C)</p> Signup and view all the answers

Which of the following correctly describes the response of B cells to TI antigens?

<p>They produce predominantly low-affinity IgM antibodies (B)</p> Signup and view all the answers

What type of B cells predominantly respond to thymus-independent antigens?

<p>Marginal zone B cells (B)</p> Signup and view all the answers

To what does the term 'thymus-dependent antigens' refer?

<p>Proteins that require THelper cell interaction for B cell activation (B)</p> Signup and view all the answers

Which of the following signals is crucial for B cell differentiation into plasma cells?

<p>Second signal from THelper cells (C)</p> Signup and view all the answers

What role does IL-21 play in the activation of B cells?

<p>Promotes B cell proliferation and differentiation (B)</p> Signup and view all the answers

Which statement about linked recognition is true?

<p>It necessitates the physical association of the peptide recognized by T cells with the antigen recognized by BCR. (A)</p> Signup and view all the answers

Where do the primary foci of activated B cells develop?

<p>In the medullary cord of the lymph node and red pulp of the spleen (B)</p> Signup and view all the answers

What is the function of centrocytes in the germinal centre?

<p>To reduce their rate of division and reenter the light zone (D)</p> Signup and view all the answers

What distinguishes secondary lymphoid follicles from primary lymphoid follicles?

<p>Existence of germinal centres and their supportive structures (A)</p> Signup and view all the answers

What role do follicular dendritic cells (FDC) play in the immune response?

<p>They express complement receptors and trap immune complexes. (D)</p> Signup and view all the answers

What occurs when activated B cells downregulate CCR7?

<p>They initiate plasmablast formation. (C)</p> Signup and view all the answers

What is a characteristic feature of plasma cells after differentiation?

<p>They migrate to the bone marrow to produce antibodies continuously. (C)</p> Signup and view all the answers

Which cytokine signaling is associated with regulating antibody class-switching?

<p>IL-4 (D)</p> Signup and view all the answers

Which receptor is crucial for the retention of centroblasts in the dark zone of the germinal centre?

<p>CXCR4 (B)</p> Signup and view all the answers

Antigens that require THelper cell function to induce B cell activation are called ______ antigens.

<p>thymus-dependent</p> Signup and view all the answers

Antigens that activate B cells without THelper cell involvement are referred to as ______ antigens.

<p>thymus-independent</p> Signup and view all the answers

TI-1 antigens activate B cells via the ______ receptors.

<p>TLR</p> Signup and view all the answers

The B cell co-receptor complex includes CD19, CD21, and ______.

<p>CD81</p> Signup and view all the answers

Responses to TI antigens are primarily made by the non-recirculating ______ B cells.

<p>marginal zone</p> Signup and view all the answers

B cells activated through thymus-independent antigens produce low affinity antibodies of the ______ class.

<p>IgM</p> Signup and view all the answers

Binding of CD21 to C3b-opsonized pathogens aids in the binding of the ______ to the same pathogen.

<p>BCR</p> Signup and view all the answers

TI-2 antigens activate B cells by cross-linking a critical number of ______.

<p>BCRs</p> Signup and view all the answers

TFH cells provide several signals that activate B cells and promote their differentiation, including activation of CD40 to induce ______ activation.

<p>NFκB</p> Signup and view all the answers

Naïve B cells express ______ and localize to the follicles while its ligand is produced by FDCs.

<p>CXCR5</p> Signup and view all the answers

Activated B cells that receive T cell help will downregulate CCR7 and migrate away from the ______ with the T cell zone.

<p>boundary</p> Signup and view all the answers

The process through which T cells recognize the same antigen as the B cells is called ______ recognition.

<p>linked</p> Signup and view all the answers

Primary foci of activated B cells are located within the medullary ______ in the lymph node.

<p>cord</p> Signup and view all the answers

After activation, some B cells can form germinal centres which are sites for sustained B cell ______ and differentiation.

<p>proliferation</p> Signup and view all the answers

Centroblasts in the germinal centre express CXCR4 and CXCR5 and are retained in the dark zone by the chemokine ______.

<p>CXCL12</p> Signup and view all the answers

Activated B cells in germinal centres differentiate into long-lived ______ cells, which produce antibodies.

<p>plasma</p> Signup and view all the answers

The ______ zone of a germinal centre consists of resting B cells pushed to the periphery by activated cells in the centre.

<p>mantle</p> Signup and view all the answers

Cytokines like IL-21 signaling promote B cell ______ and differentiation into plasma cells.

<p>proliferation</p> Signup and view all the answers

Flashcards

B cell activation signals

B cells need two signals for activation: one from the B cell receptor (BCR) and another involving T helper cells (or microbial antigens).

TD antigens

Antigens that need T helper cells (TFH cells) to activate B cells; mostly protein antigens.

TI antigens

Antigens that activate B cells without T helper cells; generally have repetitive structures.

TI-1 antigens

TI antigens that induce B cell proliferation and differentiation non-specifically (polyclonal activation), often via TLR activation.

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TI-2 antigens

TI antigens with highly repetitive structures that activate B cells by crosslinking multiple B cell receptors.

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B cell co-receptor complex

A group of proteins (CD19, CD81, CD21) that enhances the B cell receptor's signal and helps with pathogen recognition.

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Antigen processing and presentation

B cells take antigens, break them down, and display them on their surface to MHC class II molecules.

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TFH cells

T helper cells that help activate and regulate B cells; essential for TD antigen activation.

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TFH cell role

TFH cells aid B cell activation and differentiation after recognizing peptide:MHC class II complexes.

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Linked Recognition

B cell activation by T cell when both recognize antigen parts on the same complex molecule; they work in tandem.

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Primary focus

Early B cell aggregate during differentiation, mainly IgM antibody production.

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Germinal Center

A specialized B cell aggregate that promotes B cell proliferation and a wider antibody response.

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Plasma cell

Long-lived, antibody-producing immune cells resulting from B cell differentiation.

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Plasmablast

An activated B cell that begins IgM antibody production but can further interact with T cells.

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Centrocyte

B cell in germinal center that undergoes antibody affinity maturation.

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Follicular Dendritic Cells (FDCs)

Cells in lymph nodes that trap immune complexes containing antigens to allow for B cell interaction.

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CD40 Signaling

Essential for B cell survival and activation through NFkB pathway.

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Cytokine Role

Cytokines like IL-21, IL-4, and others regulate antibody class switching and B cell development.

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TD Antigen

Antigen requiring T helper cells for B cell activation; mostly proteins.

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TI Antigen

Antigen activating B cells without T helper cells; often repetitive structures.

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TI-1 Antigen

TI antigen causing non-specific B cell activation (polyclonal).

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TI-2 Antigen

TI antigen with repetitive structures; activates many BCRs simultaneously.

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BCR Signal

One needed signal during B cell activation, initiated from BCR.

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B Cell Co-receptor

CD19, CD81, CD21 complex; enhances BCR signaling, helps pathogen recognition.

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Antigen Presentation

B cells process and present antigens using MHC class II molecules.

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TFH Cell Role

TFH cells recognize antigen-MHC complex, providing second signal for B cell activation/differentiation.

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TFH cell signal

TFH cells activate B cells after recognizing peptide:MHC class II complexes, providing signals such as CD40 activation, cytokines (IL-21, IL-4, etc.) and promoting survival.

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Linked recognition

B cells getting help from T helper cells (TFH) when both recognize different parts of the same antigen.

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Primary Focus

Early B cell aggregate in lymph nodes where activated B cells proliferate and differentiate into plasmablasts.

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Germinal center

Specialized area in lymphoid follicles where activated B and T helper cells get together to refine B cells and diversify antibodies through affinity maturation

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Plasma cells

Long-lived antibody-producing cells created by differentiated B cells, residing in the bone marrow.

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Plasmablasts

Short-lived activated B cells that produce antibodies, primarily IgM, and can interact with TFH cells before becoming plasma cells.

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Follicular Dendritic Cells (FDCs)

Cells in lymph nodes that trap immune complexes, allowing B cells to recognize antigens.

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CD40 signaling

A key signal for B cell activation and survival; it activates NF-κB pathways and expression of anti-apoptotic molecules.

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Cytokine Role

Various cytokines, like IL-21, regulate B cell proliferation, differentiation, and antibody class switching.

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Centrocyte

B cell in the germinal center that undergoes antibody affinity maturation by undergoing further cell division and interactions enabling improved antibody specificity.

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B cell activation signals

B cells are activated by two signals: one from their B cell receptor (BCR) and another from T helper cells (or microbial antigens).

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TD antigen

Antigens requiring T helper cell (TFH) function for B cell activation, typically proteins.

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TI antigen

Antigens activating B cells without T helper cells; often highly repetitive structures.

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TI-1 antigen

TI antigens causing non-specific B cell activation (polyclonal activation), often through Toll-like receptor (TLR) activation.

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TI-2 antigen

TI antigens with repetitive structures; activate B cells by simultaneously cross-linking many B cell receptors (BCRs).

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B cell co-receptor complex

A complex of CD19, CD81, and CD21 proteins that enhances B cell receptor (BCR) signaling and helps recognize pathogens.

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Antigen processing and presentation

The process of B cells breaking down antigens and displaying them on their surface using MHC class II molecules.

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TFH cell role

T helper cells (TFH) recognize antigen-MHC complexes on B cells, providing the second signal for B cell activation and differentiation into plasma cells.

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TFH cell signal

TFH cells provide crucial signals after recognizing peptide-MHC II complexes for B cell activation and differentiation, enabling antibody production.

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Linked Recognition

B cells and T helper cells (TFH) work together to recognize different parts of the same antigen, promoting B cell activation.

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Primary Focus

An early aggregate of activated B cells in lymph nodes where they proliferate and differentiate into plasmablasts, producing antibodies, mainly IgM initially.

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Germinal Center

A specialized area in lymphoid follicles where activated B cells and T helper cells interact to refine B cells through antibody affinity maturation, enhancing antibody specificity.

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Plasma Cells

Long-lived, antibody-producing cells resulting from B cell differentiation, residing mainly in bone marrow.

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Plasmablasts

Activated B cells that begin producing antibodies (primarily IgM) but can still interact with T helper cells, crucial for further antibody development.

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Follicular Dendritic Cells (FDCs)

Cells in lymph nodes that trap immune complexes containing antigens to allow for B cell interaction and signaling.

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CD40 Signaling

A crucial signal for B cell survival and activation, leading to NF-κB activation and expression of anti-apoptotic molecules.

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Cytokine Role

Various cytokines, such as IL-21, play a vital role in regulating B cell proliferation, differentiation, and antibody class switching.

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Centrocyte

B cells in germinal centers that undergo antibody affinity maturation through further cell division and interaction; improving antibody specificity.

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