8.1 Humoral Immunity

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What is the primary defense mechanism used to combat microbes in the lumens of mucosal organs and in newborn fetus?

Antibodies (correct)

Macrophages

Complement proteins

Cellular receptors

Which type of receptors do antibodies against microbes and microbial toxins block to prevent their binding?

Cellular receptors (correct)

Complement receptors

NK cell receptors

IgE receptors

Which receptor is involved in the killing of helminths through IgE-mediated mechanisms?

FcγRI (CD64)

FcεRI (IgE)

Fcδ (IgE) (correct)

FcγRIII (CD16)

What is the main molecule responsible for complement activation in the classical pathway?

Antibodies Signup and view all the answers

Which immune response mechanism primarily relies on leukocyte Fc receptors for Antibody-Dependent Cell-Mediated Cytotoxicity (ADCC)?

NK cell receptors Signup and view all the answers

What is the role of the CR2 coreceptor on B cells?

Facilitates B cell activation Signup and view all the answers

What enhances B cell activation alongside the CR2 coreceptor?

Engagement of Toll-like receptors by microbial products Signup and view all the answers

What occurs when the BCR internalizes bound antigens into endosomal vesicles?

Antigens are processed into peptides presented by class II MHC molecules Signup and view all the answers

Which receptor is engaged by microbial products to enhance B cell activation?

Toll-like receptors (TLRs) Signup and view all the answers

What is the initial step in initiating immune responses according to the text?

Recognition of antigens by helper T cells and B cells Signup and view all the answers

In T cell–dependent antibody responses, where do activated lymphocytes interact?

At the interface of T and B cell zones Signup and view all the answers

What is the role of T-independent antigens in the generation of natural antibodies?

They contribute to the production of antibodies without requiring exposure to pathogens. Signup and view all the answers

Which antibody feedback mechanism involves the formation of antigen-antibody complexes that bind to inhibitory Fc receptors on B cells?

Antibody feedback Signup and view all the answers

How do secreted IgG antibodies inhibit continuing B cell activation?

By binding to inhibitory Fc receptors on B cells Signup and view all the answers

What is the function of the cytoplasmic tail of FcγRIIB in B cell activation?

Inhibiting the activation of B cells Signup and view all the answers

How do activated Th cells interact with B cells in humoral immune responses?

By engaging CD40L on B cells Signup and view all the answers

What is the primary role of activated Th cells during humoral immune responses?

To secrete cytokines that bind to cytokine receptors on B cells Signup and view all the answers

What is the primary function of IgA antibodies?

To prevent microbes from entering through epithelia Signup and view all the answers

What is the role of CD40 signals in antibody response?

To induce isotype switching Signup and view all the answers

What is the key enzyme required for isotype switching?

AID (activation-induced (cytidine) deaminase) Signup and view all the answers

What is the process that leads to increased affinity of antibodies for a particular antigen?

Affinity maturation Signup and view all the answers

What is the primary function of IgE antibodies?

To participate in elimination of helminths and hypersensitivity reactions Signup and view all the answers

What is the process of switch recombination in B cells?

The process of cutting and recombining the Ig heavy chain DNA in B cells Signup and view all the answers

Which type of immune response results in more durable, high-affinity antibodies?

T-dependent response Signup and view all the answers

Which B cells respond preferentially to protein antigens?

Follicular B cells (B2 cells) Signup and view all the answers

What type of B cells recognize multivalent antigens, such as bloodborne polysaccharides?

Marginal zone B cells Signup and view all the answers

What is the main difference between primary and secondary antibody responses?

Primary responses result from the activation of naive B cells, whereas secondary responses are due to the stimulation of expanded clones of memory B cells Signup and view all the answers

What type of antibody is mostly produced in T-independent responses?

IgM antibodies Signup and view all the answers

Which type of immune response is slower to develop but results in more durable, high-affinity antibodies?

T-dependent response Signup and view all the answers

What type of lymphocytes are independently recognized by specific protein antigens in secondary lymphoid organs?

Naive B cells Signup and view all the answers

Where do activated helper T cells and activated B cells migrate towards each other to initiate humoral immune responses?

Follicles Signup and view all the answers

Which type of cells recognize MHC-peptide complexes on B cells and stimulate B cell responses?

Helper T cells Signup and view all the answers

What type of B cell proliferation results in the formation of an extrafollicular focus?

Activated B cell proliferation Signup and view all the answers

Where do germinal centers form during T cell-dependent antibody responses to protein antigens?

Follicles Signup and view all the answers

What is the primary function of naive CD4+ T cells during helper T cell-dependent antibody responses?

Activate in T cell zones Signup and view all the answers

Where does B cell activation occur initially in response to protein antigens?

Extrafollicular foci Signup and view all the answers

Which receptor does CD40 ligand (CD40L) interact with on B cells to induce their proliferation and differentiation?

CD40 Signup and view all the answers

What is the primary role of extrafollicular foci of T-dependent B cell activation?

Limit the spread of infection Signup and view all the answers

Where do extrafollicular foci develop in the spleen during B cell activation?

T cell–rich PALS Signup and view all the answers

Which immune cells are responsible for generating antibody-secreting plasma cells in extrafollicular foci?

B cells Signup and view all the answers

What is a characteristic feature of the antibodies generated in the extrafollicular foci?

Low-affinity Signup and view all the answers

What is the final destination of plasmablasts generated in germinal centers?

Bone marrow Signup and view all the answers

What is the major site of long-lived plasma cell differentiation?

Bone marrow Signup and view all the answers

What major structural alterations occur during the differentiation of B cells into antibody-secreting plasma cells?

Increased Ig production Signup and view all the answers

Where do mature plasma cells primarily secrete antibodies?

Blood circulation Signup and view all the answers

What effect does the differentiation into plasma cells have on the size of the cell?

Cell size increases dramatically Signup and view all the answers

What is the main role of long-lived plasma cells in providing protection?

Producing antibodies for immediate protection Signup and view all the answers

What is the term used to describe the process where activated B cells produce antibodies that bind to antigens with increasing affinity?

Affinity maturation Signup and view all the answers

What type of immune response is primarily stimulated by helper T cells in response to protein antigens?

T-dependent antibody response Signup and view all the answers

Which type of antigens can activate B cells without T cell help, characterized by repeating determinants such as polysaccharides?

T-independent antigens Signup and view all the answers

What is the main molecule responsible for complement activation in the classical pathway during a humoral immune response?

Immunoglobulin M (IgM) Signup and view all the answers

Which process leads to the production of long-lived plasma cells and memory B cells in the humoral immune response?

Helper T cell stimulation Signup and view all the answers

Which type of B cells respond preferentially to multivalent antigens such as bloodborne polysaccharides?

Marginal zone B cells Signup and view all the answers

What is the role of CXCR5 in the differentiation of T cells?

It indirectly influences the differentiation of T cells through its expression on activated T cells Signup and view all the answers

Which of the following factors influences the differentiation of T cells into either Th1, Th2, Th17, or Tfh cells?

The strength of the interaction between DCs and naive CD4+ T cells Signup and view all the answers

What is the primary event that occurs in a germinal center reaction?

Affinity maturation Signup and view all the answers

Which of the following steps is NOT part of the germinal center reaction?

Formation of antigen-antibody complexes Signup and view all the answers

What is the role of initial activation by antigen-presenting DCs in the differentiation of T cells?

It directly activates naive CD4+ T cells to differentiate into T cells Signup and view all the answers

Which type of immune response results in more durable, high-affinity antibodies?

Secondary antibody response Signup and view all the answers

8.1 Humoral Immunity

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Questions and Answers

What is the primary defense mechanism used to combat microbes in the lumens of mucosal organs and in newborn fetus?

Which type of receptors do antibodies against microbes and microbial toxins block to prevent their binding?

Which receptor is involved in the killing of helminths through IgE-mediated mechanisms?

What is the main molecule responsible for complement activation in the classical pathway?

Which immune response mechanism primarily relies on leukocyte Fc receptors for Antibody-Dependent Cell-Mediated Cytotoxicity (ADCC)?

What is the role of the CR2 coreceptor on B cells?

What enhances B cell activation alongside the CR2 coreceptor?

What occurs when the BCR internalizes bound antigens into endosomal vesicles?

Which receptor is engaged by microbial products to enhance B cell activation?

What is the initial step in initiating immune responses according to the text?

In T cell–dependent antibody responses, where do activated lymphocytes interact?

What is the role of T-independent antigens in the generation of natural antibodies?

Which antibody feedback mechanism involves the formation of antigen-antibody complexes that bind to inhibitory Fc receptors on B cells?

How do secreted IgG antibodies inhibit continuing B cell activation?

What is the function of the cytoplasmic tail of FcγRIIB in B cell activation?

How do activated Th cells interact with B cells in humoral immune responses?

What is the primary role of activated Th cells during humoral immune responses?

What is the primary function of IgA antibodies?

What is the role of CD40 signals in antibody response?

What is the key enzyme required for isotype switching?

What is the process that leads to increased affinity of antibodies for a particular antigen?

What is the primary function of IgE antibodies?

What is the process of switch recombination in B cells?

Which type of immune response results in more durable, high-affinity antibodies?

Which B cells respond preferentially to protein antigens?

What type of B cells recognize multivalent antigens, such as bloodborne polysaccharides?

What is the main difference between primary and secondary antibody responses?

What type of antibody is mostly produced in T-independent responses?

Which type of immune response is slower to develop but results in more durable, high-affinity antibodies?

What type of lymphocytes are independently recognized by specific protein antigens in secondary lymphoid organs?

Where do activated helper T cells and activated B cells migrate towards each other to initiate humoral immune responses?

Which type of cells recognize MHC-peptide complexes on B cells and stimulate B cell responses?

What type of B cell proliferation results in the formation of an extrafollicular focus?

Where do germinal centers form during T cell-dependent antibody responses to protein antigens?

What is the primary function of naive CD4+ T cells during helper T cell-dependent antibody responses?

Where does B cell activation occur initially in response to protein antigens?

Which receptor does CD40 ligand (CD40L) interact with on B cells to induce their proliferation and differentiation?

What is the primary role of extrafollicular foci of T-dependent B cell activation?

Where do extrafollicular foci develop in the spleen during B cell activation?

Which immune cells are responsible for generating antibody-secreting plasma cells in extrafollicular foci?

What is a characteristic feature of the antibodies generated in the extrafollicular foci?

What is the final destination of plasmablasts generated in germinal centers?

What is the major site of long-lived plasma cell differentiation?

What major structural alterations occur during the differentiation of B cells into antibody-secreting plasma cells?

Where do mature plasma cells primarily secrete antibodies?

What effect does the differentiation into plasma cells have on the size of the cell?

What is the main role of long-lived plasma cells in providing protection?

What is the term used to describe the process where activated B cells produce antibodies that bind to antigens with increasing affinity?

What type of immune response is primarily stimulated by helper T cells in response to protein antigens?

Which type of antigens can activate B cells without T cell help, characterized by repeating determinants such as polysaccharides?

What is the main molecule responsible for complement activation in the classical pathway during a humoral immune response?

Which process leads to the production of long-lived plasma cells and memory B cells in the humoral immune response?

Which type of B cells respond preferentially to multivalent antigens such as bloodborne polysaccharides?

What is the role of CXCR5 in the differentiation of T cells?

Which of the following factors influences the differentiation of T cells into either Th1, Th2, Th17, or Tfh cells?

What is the primary event that occurs in a germinal center reaction?

Which of the following steps is NOT part of the germinal center reaction?

What is the role of initial activation by antigen-presenting DCs in the differentiation of T cells?

Which type of immune response results in more durable, high-affinity antibodies?

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