IMSE Lecture Week 03: B Cell Maturation

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Questions and Answers

What is the role of phagocytic cells in the internal innate immune system?

They produce antibodies.

They engulf and digest pathogens. (correct)

They release cytokines to B cells.

They block pathogens from entering the body.

Which component of the immune system is responsible for the quick, non-specific response?

Antibodies

Cytokines

Innate immune system (correct)

Adaptive immune system

What do B cells do after receiving information from cytokines?

Present antigens to APCs.

Activate T cells.

Produce antibodies. (correct)

Engulf pathogens.

Which of the following is NOT a feature of the adaptive immune system?

Provides a quick response. Signup and view all the answers

What are Toll-like receptors primarily responsible for?

Recognizing and binding to pathogenic products. Signup and view all the answers

Which of the following cells is considered a pathogen recognition receptor (PRR)?

Macrophages Signup and view all the answers

How do antibodies assist in the internal innate immune system?

By enhancing innate immunity function. Signup and view all the answers

What do pathogen-associated molecular patterns (PAMPs) help the innate immune system to do?

Recognize specific types of pathogens. Signup and view all the answers

What is the primary function of Pro-B cells?

Rearrangement of genes coding for antibody chains Signup and view all the answers

Which markers are characteristic of Immature B cells?

Complete IgM and CD21 Signup and view all the answers

In which stage of B cell maturation are antibody production activities most prominent?

Plasma cells Signup and view all the answers

Which types of chains are included in the basic structure of an antibody?

Light and heavy chains Signup and view all the answers

Where are plasma cells predominantly found?

In the germinal center of lymphoid organs and bone marrow Signup and view all the answers

What is the primary function of primary lymphoid organs?

Maturation of B and T cells Signup and view all the answers

Which type of bone marrow increases in volume as a person ages?

Yellow marrow Signup and view all the answers

What are the two main types of splenic tissue?

Red pulp and white pulp Signup and view all the answers

Where are naive B cells primarily located in the spleen?

Primary follicles Signup and view all the answers

Which primary lymphoid organ is crucial for T cell maturation?

Thymus Signup and view all the answers

What is the function of lymph nodes in the immune system?

Filtering lymph fluid and providing antigen contact Signup and view all the answers

Which part of the lymph node contains plasma cells and memory B cells?

Germinal center Signup and view all the answers

Which components are part of the Mucosal-associated lymphoid tissue (MALT)?

Tonsils, appendix, Peyer’s patches Signup and view all the answers

Study Notes

Innate Immune System

Functions from birth, providing a rapid, non-specific response to pathogens.
Divided into external and internal systems.

External Innate Immune System

Acts as the first line of defense against pathogens.
Key components include:
- Skin
- Mucous membranes
- Normal flora
- Secretions

Internal Innate Immune System

Utilizes phagocytic cells to engulf and digest invading pathogens.
Antigen-Presenting Cells (APCs) carry antigen information to the adaptive immune system for antibody production.

Adaptive Immune System

Targets specific pathogens and creates memory for quicker future responses.
T cells release cytokines to activate B cells after interacting with APCs.
B cells produce antibodies for rapid response to re-infection.
Antibodies enhance the function of the internal innate immune system.

Key Players in Innate Immunity

Natural Killer (NK) cells attack virus-infected and cancerous cells.
Pathogen-associated Molecular Patterns (PAMPs) can detect various microbial structures (e.g., peptidoglycan, lipoproteins).
Toll-like receptors (TLRs) recognize pathogenic products, enhancing immune response.

Organs of the Immune System

Divided into primary and secondary lymphoid organs for maturation and activation of B and T cells.

Primary Lymphoid Organs

Bone Marrow:
- Largest tissue, producing blood cells.
- Comprises yellow (fat) and red (blood) marrow; yellow marrow increases with age.
Thymus:
- Small, bilobed organ in the thorax, shrinks with age and functions also as an endocrine organ.

Secondary Lymphoid Organs

Spleen:
- Largest secondary lymphoid organ; filters blood, removing old or damaged cells.
- Contains red pulp (for culling) and white pulp (lymphoid tissue).
- T and B cells are located strategically around arterioles and in follicles.
Lymph Nodes:
- Junctional filters of the lymphoid system.
- Ideal for antigen contact; filters lymph fluid.
- Composed of outer cortex with macrophages, T cells in paracortex, and germinal centers with B cells.
MALT (Mucosal-associated lymphoid tissue):
- Located in gastrointestinal, respiratory, and urogenital tracts.
- Contains structures like tonsils, appendix, and Peyer’s patches.

B Cell Maturation

Pro-B Cell:
- Influenced by growth factors like IL7.
- Markers include CD19, CD45R, and RAG enzymes.
- Main role is gene rearrangement for antibody heavy and light chains.
Pre-B Cell:
- Characterized by a receptor made of heavy and surrogate light chains.
- Main function is the synthesis of the heavy chain (μ).
Immature B Cell:
- Contains complete IgM, CD21, and Class II MHC.
- Prepares for antigen-specific responses.
Mature B Cell:
- Expresses complete IgM and IgD with MHC Class II.
- Waits in secondary lymphoid organs for activation.
Plasma Cell:
- Produces abundant antibodies but has little surface Ig.
- Found in germinal centers or bone marrow; crucial for antibody production.

Antibody Structure

Comprised of a tetrapeptide with heavy and light chains.
Heavy chains consist of five antigenic types (Ig gamma, alpha, mu, delta, epsilon).
Light chains are classified into two types: kappa and lambda.

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Description

This quiz covers the maturation of B cells within the innate immune system. It explores both external and internal defense mechanisms, including skin barriers and phagocytic cells. Test your understanding of how the immune system responds to pathogens from birth.