209 11-18-24

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Questions and Answers

What type of immunity is characterized by memory, specificity, diversity, and tolerance?

Innate immunity

Adaptive immunity (correct)

Acute immunity

Passive immunity

What is the primary role of B lymphocytes in the adaptive immune response?

They directly kill pathogens.

They act as phagocytes.

They produce antibodies. (correct)

They activate T cells.

What is the primary function of most activated lymphocytes?

Generating diverse antigens

Secreting antibodies (correct)

Producing long-lived memory cells

Stimulating T cell activation

How is the diversity of antibody specificities generated?

Through random combinations of gene segments (C) Signup and view all the answers

What are the polypeptide chains that make up antibodies referred to as?

Light and heavy chains (A) Signup and view all the answers

Which process allows for the proliferation and differentiation of lymphocytes that bind specifically to antigens?

Clonal selection (D) Signup and view all the answers

What role do T cells play in B cell activation?

They supply signals through cytokines and receptor interactions (C) Signup and view all the answers

What type of cells are produced from bone marrow stem cells?

All immune cells including lymphocytes (A) Signup and view all the answers

Where does the proliferation and activation of mature B cells typically occur?

In 2° lymphoid tissue, such as lymph nodes (D) Signup and view all the answers

What is required for the unique antigen-binding site formation in antibodies?

Recombination of V, D, and J gene segments (A) Signup and view all the answers

What is considered an antigen?

Any molecule that stimulates an adaptive immune response (B) Signup and view all the answers

What initiates the switch in isotype class of antibodies produced by B cells?

Deletion of heavy chain constant region genes (B) Signup and view all the answers

What are the immunoglobulin chains associated with in B cell antigen receptor structure?

Signaling subunits Iga and b (C) Signup and view all the answers

Which type of cell has receptors that recognize IgG antibodies?

Natural killer cells (D) Signup and view all the answers

What determines the diversity of the adaptive immune response?

The number of different lymphocytes produced (C) Signup and view all the answers

How many different antibody specificities can the immune system potentially produce?

10 billion (B) Signup and view all the answers

What happens during receptor aggregation in B cell activation?

Activation signaling is initiated (B) Signup and view all the answers

What is the primary function of the Fc region in antibodies?

To determine structural and functional properties (B) Signup and view all the answers

What is the result of gene segment recombination in B cells?

Creation of unique antibodies with specific binding sites (D) Signup and view all the answers

How does IgA function in the intestinal lumen?

By preventing pathogen binding (D) Signup and view all the answers

What happens when Mast cells bind to IgE antibodies?

They release inflammatory mediators (B) Signup and view all the answers

What role does complement play when antibodies are bound to pathogens?

They form pores in the pathogen membrane (C) Signup and view all the answers

What is a distinguishing feature of Memory B cells?

They can rapidly respond to subsequent exposures (C) Signup and view all the answers

Which antibody class is primarily involved in allergic responses?

IgE (D) Signup and view all the answers

Study Notes

Innate vs Adaptive Immunity

Innate immunity is the body's first line of defense against pathogens.
If the innate response is insufficient, the adaptive immune response is activated.
Adaptive immunity recognizes specific pathogens and mounts a targeted response.
This process involves induction of adaptive response, which can clear pathogens, and generates immunological memory.

Immune Cell Origin

Bone marrow stem cells are the origin for all immune cells, including lymphocytes.
B and T lymphocytes are part of the adaptive immune system, distinct from innate immune cells.

Antibodies

Antibodies (immunoglobulins) are proteins produced by B lymphocytes.
They provide highly specific immunity to antigens, composed of heavy and light chains.
Different antibodies have distinct antigen-binding sites on their structures.
Any substance triggering an adaptive immune response is called an antigen.
Antigens can be proteins, carbohydrates, lipids, and nucleic acids; pathogens contain various antigens.
Each antigen typically has multiple epitopes, which are specific areas on the antigen recognized by antibodies.

Antibody Diversity

The adaptive immune system creates a huge number of diverse lymphocytes, each with a unique specificity.
Mature B cells produce antibodies with different structures not seen in other B cells.
The immune system has the potential to produce a wide array (10^11) of different antibody specificities.
Antibody diversity is generated by recombination of immunoglobulin (Ig) gene segments during B cell development in the bone marrow.
Unique combinations of V,D,J gene segments result in unique antigen-binding sites for each antibody.
Antibody heavy and light chain genes undergo recombination during B cell development.
The specific combination of gene segments in each B cell leads to unique antibody binding specificities.

Antibody Action

Antibodies have diverse mechanisms to provide immunity.
Neutralization - antibodies block pathogen adherence.
Opsonization - antibodies enhance phagocytosis.
Complement activation - antibodies activate complement, enhancing opsonization and lysis.
Directed cytotoxicity - antibodies trigger NK cell to kill target cells.

B Cell Activation

B cell proliferation and activation mostly occurs in secondary lymphoid tissues, like lymph nodes.
Activation depends on antigen recognition and the immunoglobulin receptor on the cell's surface.
Receptor aggregation signaling leads to B cell activation.
B cells generally need T-cell help to become fully activated.
T cells deliver activating signals through cytokines and cell surface receptor interactions.
B cell activation results in maturation and differentiation, either into antibody-secreting plasma cells or long-lived memory B cells.

Isotype Switching

B cell activation can cause a switch in antibody class.
B cells begin producing IgM, then can switch to IgG, IgA, or IgE.
Isotype switching alters the constant region (Fc) of the antibody, leading to structural and functional differences in the antibody.
The switch occurs by deletion of DNA sequences and does not change the antigen-binding site.

IgG Function

IgG is recognized by immune cells, macrophages, and NK cells.
Macrophages and NK cells use receptor-mediated binding to pathogens coated in IgG.
This process can cause phagocytosis or NK cell-mediated killing of the pathogen.

IgA Function

Dimeric IgA is transported across intestinal epithelium (transcytosis).
In the intestinal lumen, IgA blocks pathogens or toxins.
Transcytosis of IgA also occurs in salivary glands.

IgM and IgG Complement Activation

The Fc regions of IgM and IgG antibodies act as binding sites for complement proteins.
When antibodies bind to pathogen surfaces, complement activation is triggered. (forming pores in pathogen membranes that cause lysis)

IgE Function

IgE antibodies are bound to mast cells through Fc receptors.
Binding of antigen (allergen) triggers Mast cells to release mediators (like histamine).
This response can lead to an allergic reaction.

Memory B Cells

Memory B cells develop in response to antigen exposure.
A secondary response to the same antigen occurs quicker and with more antibodies and includes larger fractions of non-IgM antibody classes

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Description

Test your knowledge on the differences between innate and adaptive immunity. This quiz covers the origin of immune cells, the role of antibodies, and the adaptive immune response's mechanisms. Prepare to explore how your body defends against specific pathogens!