p.5
Activation and Proliferation of Lymphocytes
What is the role of regulatory T cells in the immune system?
They suppress rather than activate lymphocytes.
p.6
Humoral vs. Cell-Mediated Immunity
What is Immunoglobulin A (IgA)?
A type of antibody abundantly produced in mucosal tissues that binds and neutralizes microbes.
p.1
Activation and Proliferation of Lymphocytes
What happens to activated or eTector lymphocytes?
They undergo proliferation and produce cytokines.
p.3
Secondary Lymphoid Organs and Their Functions
What is the role of secondary lymphoid organs in the immune system?
They initiate adaptive immune responses to microbes.
p.6
Activation and Proliferation of Lymphocytes
Where are the intraepithelial lymphocytes located?
In the mucosal epithelium.
p.12
Memory Lymphocytes and Their Functions
What are the important differences among naive, effector, and memory T and B lymphocytes?
Naive lymphocytes have not encountered their specific antigens, effector lymphocytes are actively involved in the immune response, and memory lymphocytes persist long-term to provide a faster response upon re-exposure to the antigen.
p.12
Secondary Lymphoid Organs and Their Functions
How is the anatomic separation between T and B lymphocytes maintained in lymph nodes?
This separation is maintained by distinct microenvironments and specialized structures within the lymph node.
p.10
B Lymphocyte Activation and Antibody Production
What do B lymphocytes differentiate into after recognizing and responding to antigens?
Antibody-secreting plasma cells.
p.2
Activation and Proliferation of Lymphocytes
What happens to naive T cell output as individuals age?
It gradually reduces due to thymic involution after puberty.
p.2
Role of Antigen-Presenting Cells (APCs)
What type of cells are specialized in capturing and presenting antigens to lymphocytes?
Antigen-Presenting Cells (APCs), primarily dendritic cells.
p.6
Differences Between Innate and Adaptive Immunity
What are the major components of the cutaneous immune system?
Keratinocytes, Langerhans cells, and intraepithelial lymphocytes.
p.10
Memory Lymphocytes and Their Functions
What are Memory T cells capable of doing?
Mount secondary responses to captured antigens and respond rapidly to infections.
p.3
Humoral vs. Cell-Mediated Immunity
How do helper T cells and B lymphocytes interact within secondary lymphoid organs?
Helper T cells specific for a protein antigen assist B lymphocytes specific for the same antigen, leading to antibody production.
p.1
Humoral vs. Cell-Mediated Immunity
What is the primary function of CD8+ T cells?
To kill infected host cells.
p.7
Secondary Lymphoid Organs and Their Functions
Where are T lymphocytes concentrated in the spleen?
In periarteriolar lymphoid sheaths surrounding small arterioles.
p.5
Role of Antigen-Presenting Cells (APCs)
What is the function of M cells in the mucosal immune system?
They promote the transport of antigens from the lumen into underlying tissues.
p.2
Cytokines and Their Role in Immune Responses
What role do cytokines play in memory T cells?
They are involved in generating and maintaining memory cells.
p.2
Role of Antigen-Presenting Cells (APCs)
How do dendritic cells function in the immune response?
They capture antigens, transport them to secondary lymphoid organs, and present them to T lymphocytes.
p.4
Secondary Lymphoid Organs and Their Functions
What is lymph and its primary function?
Fluid that leaks out of small blood vessels and is drained by lymphatic vessels to lymph nodes, containing substances absorbed from tissues.
p.10
Memory Lymphocytes and Their Functions
Where do some Memory T cells permanently reside?
Epithelial tissues, such as mucosal tissues and skin.
p.7
Role of Antigen-Presenting Cells (APCs)
Where do dendritic cells present antigens to T lymphocytes?
In the parafollicular cortex.
p.10
Differences Between Innate and Adaptive Immunity
What constitutes innate immunity?
The early line of defense mediated by cells and molecules that are always present.
p.11
Role of Antigen-Presenting Cells (APCs)
What do antigen-presenting cells (APCs) do?
Capture and display antigens for recognition by T cells.
p.11
B Lymphocyte Activation and Antibody Production
Where do plasma cells remain to secrete antibodies?
In lymphoid organs and the bone marrow.
p.6
Differences Between Innate and Adaptive Immunity
What cells provide immune defense against invading microbes?
Dendritic cells, T lymphocytes, and macrophages.
p.6
Secondary Lymphoid Organs and Their Functions
Where are T lymphocytes and B lymphocytes segregated in secondary lymphoid organs?
Into different anatomic regions such as follicles and paracortex in lymph nodes.
p.4
Secondary Lymphoid Organs and Their Functions
What are lymph nodes?
Encapsulated nodular aggregates of lymphoid tissues located along lymphatic channels throughout the body.
p.3
Migration Patterns of Lymphocytes
How do T and B lymphocytes locate microbes in the body?
They travel via the blood to secondary lymphoid organs and other tissues.
p.9
Memory Lymphocytes and Their Functions
What happens to naive T cells that do not encounter specific antigens in the lymph nodes?
They leave the lymph nodes through lymphatic vessels and reenter circulation.
p.3
Secondary Lymphoid Organs and Their Functions
What is one important function of lymphoid organs regarding T and B cells?
To bring together rare T and B cells specific for the same antigen after stimulation.
p.7
Activation and Proliferation of Lymphocytes
How do activated B and T cells interact after exposure to an antigen?
They migrate toward each other and meet at the edge of follicles.
p.11
Types of T Lymphocytes
What is the function of effector T lymphocytes?
To eliminate infectious microbes at peripheral sites of infection.
p.3
Secondary Lymphoid Organs and Their Functions
What is the primary function of the generative lymphoid organs?
Where T and B lymphocytes mature and become competent to respond to antigens.
p.2
B Lymphocyte Activation and Antibody Production
What can B lymphocytes recognize?
The antigens of microbes, either released or on the surface.
p.4
Role of Antigen-Presenting Cells (APCs)
What role do antigen-presenting cells (APCs) play in lymph nodes?
They sample the antigens of microbes as lymph passes through the lymph nodes.
p.3
Types of T Lymphocytes
Where are the majority of lymphocytes found in a healthy human?
In lymphoid organs and other tissues.
p.10
Adaptive Immunity and Its Functions
What is the main role of adaptive immunity?
Mediated by lymphocytes stimulated by microbial antigens, leading to proliferation and differentiation.
p.10
Activation and Proliferation of Lymphocytes
What are the phases of adaptive immune responses?
Antigen recognition, activation, elimination of microbes, decline of response, and generation of long-lived memory.
p.11
Migration Patterns of Lymphocytes
What happens to naive lymphocytes in secondary lymphoid organs?
They may encounter foreign antigens.
p.8
Humoral vs. Cell-Mediated Immunity
What is the role of antibodies secreted by plasma cells in mucosal organs?
They combat ingested and inhaled microbes.
p.2
Memory Lymphocytes and Their Functions
What triggers memory T cells to become effector cells?
Encountering the same antigen that induced their development.
p.9
Secondary Lymphoid Organs and Their Functions
Where do T cells remain after exiting the high endothelial venules?
In the paracortex of the lymph node.
p.2
Role of Antigen-Presenting Cells (APCs)
Which cells can also capture antigens to display to B cells?
Macrophages and dendritic cells in secondary lymphoid organs.
p.6
Secondary Lymphoid Organs and Their Functions
What are the cells concentrated around the periphery of lymph nodes?
B cells in discrete structures called follicles.
p.4
Secondary Lymphoid Organs and Their Functions
What are tonsils and Peyer's patches?
Discrete collections of lymphocytes and APCs in mucosal lymphoid tissues.
p.4
Differences Between Innate and Adaptive Immunity
How do cutaneous and mucosal immune systems respond to pathogens?
They respond to pathogens while avoiding reactions to harmless commensal microbes.
p.7
Secondary Lymphoid Organs and Their Functions
What is the significance of the anatomical organization of secondary lymphoid organs?
It regulates immune responses after stimulation by antigens.
p.12
Migration Patterns of Lymphocytes
How do naive and effector T lymphocytes differ in their patterns of migration?
Naive T lymphocytes migrate to lymph nodes to encounter antigens, while effector T lymphocytes migrate to sites of infection or inflammation to exert their functions.
p.9
Migration Patterns of Lymphocytes
What is the function of high endothelial venules (HEVs) in lymph node entry?
They allow mature naive T lymphocytes to migrate into lymph nodes.
p.9
Migration Patterns of Lymphocytes
What attracts T cells to stay in the paracortex of lymph nodes?
Chemokines produced in that location.
p.1
B Lymphocyte Activation and Antibody Production
What is the affinity of antibodies produced by activated B lymphocytes during an immune response?
Increases during the immune response.
p.6
Differences Between Innate and Adaptive Immunity
What type of lymphocyte is located in the dermis of the cutaneous immune system?
T lymphocytes and dendritic cells.
p.1
Memory Lymphocytes and Their Functions
What allows memory lymphocytes to survive for long periods?
They are generated from antigen-stimulated lymphocytes and can survive in the absence of antigen.
p.10
Activation and Proliferation of Lymphocytes
How are different populations of lymphocytes distinguished?
By the surface expression of particular membrane molecules.
p.8
Activation and Proliferation of Lymphocytes
What happens to naive T lymphocytes when activated by antigens?
They become effector T cells and migrate to sites of infection.
p.5
Secondary Lymphoid Organs and Their Functions
What do B cell zones in lymph nodes contain?
Numerous follicles and germinal centers.
p.9
Migration Patterns of Lymphocytes
What role do chemokines play in T cell migration within lymph nodes?
They help naive T lymphocytes bind to adhesion molecules and migrate into lymph nodes.
p.6
B Lymphocyte Activation and Antibody Production
What is found in the germinal center of a follicle?
B cells that have recently responded to a protein antigen and received signals from helper T cells.
p.10
B Lymphocyte Activation and Antibody Production
Where do many antibody-secreting plasma cells migrate to?
The bone marrow or mucosal tissues.
p.10
Secondary Lymphoid Organs and Their Functions
How does the spleen contribute to naive lymphocyte migration?
It likely follows a general pattern similar to lymph nodes, despite lacking HEVs.
p.7
Role of Antigen-Presenting Cells (APCs)
What is the role of follicular dendritic cells (FDCs) in the lymphoid organs?
They present antigens to B cells in the follicles.
p.11
Types of T Lymphocytes
What is the role of cytotoxic T lymphocytes (CTLs)?
To kill infected cells harboring microbes in the cytoplasm.
p.8
B Lymphocyte Activation and Antibody Production
What is the function of plasma cells derived from B cells?
They secrete antibodies that bind to pathogens or toxins in the blood.
p.12
Secondary Lymphoid Organs and Their Functions
Where are T and B lymphocytes located in lymph nodes?
T lymphocytes are primarily located in the paracortex, while B lymphocytes are found in the follicles.
p.3
Secondary Lymphoid Organs and Their Functions
What are the two main types of lymphoid organs in the immune system?
Generative lymphoid organs and secondary lymphoid organs.
p.6
Humoral vs. Cell-Mediated Immunity
What is the role of Paneth cells in the mucosal immune system?
They produce antimicrobial peptides.
p.4
Secondary Lymphoid Organs and Their Functions
How is the spleen similar to lymph nodes?
Both capture and concentrate antigens, but the spleen does this for blood-borne antigens.
p.10
Differences Between Innate and Adaptive Immunity
What is the primary function of the immune system?
To protect individuals from infections and cancers.
p.4
Secondary Lymphoid Organs and Their Functions
What is unique about the immune system of the skin?
It contains many immune cells without any anatomically defined structures.
p.11
Secondary Lymphoid Organs and Their Functions
Where are lymphocytes and APCs organized?
In secondary (peripheral) lymphoid organs.
p.5
Secondary Lymphoid Organs and Their Functions
What separates the white pulp from the red pulp in the spleen?
The marginal zone with its sinus.
p.2
Memory Lymphocytes and Their Functions
How do memory T cells change with age?
They increase from less than 5% in newborns to 50% or more in adults.
p.9
Activation and Proliferation of Lymphocytes
What happens when a T cell recognizes an antigen on a dendritic cell?
The T cell forms stable conjugates with the dendritic cell and gets activated.
p.3
Secondary Lymphoid Organs and Their Functions
Why is the anatomic organization of secondary lymphoid organs important?
It promotes the development of adaptive immune responses by facilitating antigen concentration and lymphocyte interaction.
p.4
Secondary Lymphoid Organs and Their Functions
What happens to blood-borne antigens in the spleen?
They are captured and concentrated by dendritic cells and macrophages.
p.4
Secondary Lymphoid Organs and Their Functions
What is the significance of cutaneous and mucosal lymphoid tissues?
They are sites of immune responses to antigens breaching epithelia and contain a large number of lymphocytes.
p.7
Activation and Proliferation of Lymphocytes
What happens to the expression of chemokine receptors upon lymphocyte activation?
They alter their expression.
p.8
Migration Patterns of Lymphocytes
What do activated T cells do after exiting lymph nodes?
They enter the bloodstream and migrate to sites of infection.
p.9
Humoral vs. Cell-Mediated Immunity
What is the primary function of T lymphocytes once they reach infected tissues?
To eradicate the microbes.
p.9
Migration Patterns of Lymphocytes
How do eTector T cells migrate to infection sites?
They enter circulation and are directed by chemokines and adhesive molecules induced by the local innate response.
p.1
Activation and Proliferation of Lymphocytes
What differentiates eTector lymphocytes from naïve lymphocytes?
eTector lymphocytes are differentiated progeny that can produce molecules to eliminate antigens.
p.8
Migration Patterns of Lymphocytes
Where do naive lymphocytes constantly recirculate?
Between the blood and secondary lymphoid organs.
p.10
Humoral vs. Cell-Mediated Immunity
What are the two components of adaptive immunity?
Humoral immunity and cell-mediated immunity.
p.8
Secondary Lymphoid Organs and Their Functions
What structures are labeled in the schematic diagram of a lymph node?
Dendritic cell, high endothelial venule, naive B cell, B cell-specific chemokine, artery, naive T cell, T cell and dendritic cell-specific chemokine, T cell zone, B cell zone, and afferent lymphatic vessel.
p.8
Migration Patterns of Lymphocytes
How do effector T cells locate and eliminate microbes?
By migrating preferentially to peripheral tissues at sites of infection and inflammation.
p.8
Migration Patterns of Lymphocytes
What is the significance of different histories of antigen exposure for lymphocyte migration?
Lymphocytes selectively migrate to sites where they can perform their respective functions.
