B cell development and activation

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Questions and Answers

What is the primary function of agglutination by antibodies?

Inducing apoptosis of infected cells

Inactivating pathogens

Impeding proliferation of pathogen

Preventing pathogen binding to cells (correct)

What is the main role of opsonization in the immune response?

Preventing pathogen binding to cells

Promoting phagocytosis (correct)

Inactivating pathogens

Inducing apoptosis of infected cells

Which antibody function involves activating Fc receptors on natural killer cells to induce apoptosis of infected cells?

Anti-body dependent cell mediated cytotoxicity (correct)

Agglutination

Degranulation

Complement activation

What is the main function of a plasma cell?

Antibody secretion Signup and view all the answers

Where does somatic hypermutation occur?

Lymph node Signup and view all the answers

During which stage of the immune response does somatic hypermutation occur?

Late primary response Signup and view all the answers

What leads to optimal B-cell activation?

Antigen binding and co-stimulatory signals from Th cells Signup and view all the answers

When does antibody class switching occur during the immune response?

After somatic hypermutation Signup and view all the answers

What is the main function of a B cell?

To secrete antibodies capable of binding to an organism, microbe or molecule Signup and view all the answers

How do plasma cells differ from mature B-cells in terms of structure and function?

Plasma cells don't have BCRs while mature B-cells do Signup and view all the answers

Which antimicrobial mechanism involves antibodies binding to a target and promoting its engulfment by phagocytic cells?

Opsonization Signup and view all the answers

What is the general role of memory B cells?

To allow for a faster and more forceful secondary response to a repeat antigen Signup and view all the answers

Which antibody class is primarily involved in immediate hypersensitivity reactions, such as allergic responses?

IgE Signup and view all the answers

Which cytokine is responsible for the initial development of B cells from hematopoietic stem cells?

IL-7 Signup and view all the answers

Which cell type is NOT derived from common lymphoid progenitors under the influence of IL-7?

Macrophages Signup and view all the answers

Which cytokine stimulates class switching to IgE?

IL-4 Signup and view all the answers

What happens if the variable region of an antibody binds with lower affinity during somatic hypermutation?

The B-cell undergoes apoptosis Signup and view all the answers

Which cytokine stimulates class switching to IgA?

TGF-beta Signup and view all the answers

What is the role of IL-21 in antibody production?

Stimulates somatic hypermutation Signup and view all the answers

What stimulates class switching to IgG subtypes?

INF-y Signup and view all the answers

Where does the B-cell move during the late primary response to undergo somatic hypermutation?

Lymph nodes Signup and view all the answers

Which antibody class is the best at activating complement system?

IgM Signup and view all the answers

Which antibody class is most relevant in secretions of the Upper respiratory tract?

IgD Signup and view all the answers

BCRs are checked for self-reactivity once and if they react to self-antigen they undergo apoptosis

False Signup and view all the answers

Immature (transitional) B-cells travel from the bone marrow to the ________

spleen Signup and view all the answers

Naive mature b-cells are sent to _______ via general circulation not lymphatic circulation

Lymph nodes Signup and view all the answers

Where do most b-cells reside inside a lymph node?

Cortex Signup and view all the answers

Where do T-cells reside inside a lymph nodes

Paracortex Signup and view all the answers

In lymph nodes, Plasma cells are found in the....

Medulla Signup and view all the answers

CD21 and CD19 help antigen bind to BCR

True Signup and view all the answers

Which co-stimulatory interaction stimulates cytokine release by Tfh?

iCOSL on B cells with iCOS on Tfh Signup and view all the answers

Study Notes

Antibody Functions and Immune Response

Agglutination by antibodies clumps pathogens together, making them easier to be recognized and eliminated by the immune system.
Opsonization enhances phagocytosis by marking pathogens for engulfment, improving the efficiency of immune response.
Fc receptor activation on natural killer (NK) cells leads to apoptosis of infected cells, a key function in fighting viral infections.
Plasma cells produce antibodies, serving as the antibody-secreting machines of the immune system.

B-Cell Activation and Somatic Hypermutation

Somatic hypermutation occurs in germinal centers of lymphoid tissues, where B cells undergo rapid mutation to enhance antibody affinity.
This process takes place during the affinity maturation phase of the immune response.
Optimal B-cell activation requires signals from T-helper cells, particularly through CD40-CD40L interaction.
Antibody class switching happens after B cells are activated and often results in different antibody isotypes to better respond to specific pathogens.

B Cell Functions and Structural Differences

The primary function of B cells is to produce antibodies that target specific antigens for immune neutralization.
Plasma cells differ from mature B cells structurally, as they have larger rough endoplasmic reticula for increased antibody production and lose their ability to express surface immunoglobulin.

Antibody Mechanisms and Memory B Cells

The antimicrobial mechanism related to engulfment involves antibodies coating pathogens (opsonization), promoting their uptake by phagocytes.
Memory B cells play a crucial role in maintaining long-term immunity by rapidly responding to previously encountered antigens upon re-exposure.

Cytokines and B Cell Development

IL-7 is vital for the initial development of B cells from hematopoietic stem cells in the bone marrow.
Common lymphoid progenitors differentiate into various immune cells; however, dendritic cells are not derived from these progenitors under IL-7 influence.
IL-4 stimulates class switching to IgE, while TGF-β induces class switching to IgA.
IL-21 enhances antibody production by stimulating B cells' growth and differentiation.

Location and Function of Antibodies

Late primary response B cells move to germinal centers for somatic hypermutation.
IgG is the antibody class best at activating the complement system, while IgA is primarily found in mucosal secretions, such as those in the upper respiratory tract.

Location within Lymph Nodes

Immature B cells transition from the bone marrow and travel to peripheral tissues.
Naive mature B cells circulate to secondary lymphoid organs, like lymph nodes, via general circulation.
Most B cells reside in the follicles of lymph nodes, while T cells are primarily located in the paracortex regions.
Plasma cells are found in the medullary cords of lymph nodes.

Co-Stimulatory Interactions

CD21 and CD19 work together to enhance antigen binding to the B-cell receptor (BCR).
Co-stimulatory interactions, particularly between Tfh cells and B cells, stimulate cytokine release, crucial for B cell activation and maturation.

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Description

Test your knowledge on antibody production and class switching, including the different cytokines secreted by T-helper cells and their induction of class switching to various immunoglobulin subtypes. This quiz material is based on Kuby Immunology (6th ed) Figure 11-19, page 271.