Activation of the Adaptive Immune Response

Questions and Answers

Which leukocytes are primarily responsible for antigen presentation?

B cells, natural killer cells, and macrophages

Dendritic cells, memory cells, and T cells

Macrophages, dendritic cells, and neutrophils (correct)

T cells, macrophages, and neutrophils

Where do T cells originate?

Spleen

Blood

Bone marrow (correct)

Thymus

What is the primary function of B cells in the adaptive immune response?

Killing pathogens

Activating T cells

Producing antibodies and memory cells (correct)

Phagocytizing foreign pathogens

During their maturation, T cells undergo which process in the thymus?

Clonal deletion Signup and view all the answers

Which statement correctly describes the relationship between T-helper cells and B cells?

T-helper cells activate B cells Signup and view all the answers

What occurs to immature T-cells after they leave the bone marrow?

They are transported to the thymus Signup and view all the answers

Where do mature T cells reside after leaving the thymus?

In both blood and lymphatic tissues Signup and view all the answers

Neutrophils are considered antigen presenting cells to a lesser extent than which of the following?

Dendritic cells and macrophages Signup and view all the answers

What is primarily activated by antigen presenting cells?

The adaptive immune response Signup and view all the answers

What type of immunity are T lymphocytes primarily associated with?

Cell-mediated immunity Signup and view all the answers

What is the primary function of cytotoxic T-cells (TC cells) in the immune response?

To induce apoptosis in virus-infected cells Signup and view all the answers

During central tolerance, what happens to T-cells and B-cells that react with self-antigens?

They undergo clonal deletion via apoptosis Signup and view all the answers

Which step in the mechanism of TC cells involves the production of perforin?

Binding to an infected cell Signup and view all the answers

What role do TH cells play in the activation of B cells?

They activate specific B cells for a particular pathogen Signup and view all the answers

What is the main purpose of B-cell proliferation during a humoral immune response?

To rapidly generate antibodies against the pathogen Signup and view all the answers

What is the function of granzyme B in the mechanism of cytotoxic T cells?

To initiate apoptosis within infected cells Signup and view all the answers

Which type of immunity is primarily mediated by antibodies in response to a pathogen?

Humoral immunity Signup and view all the answers

Which component is crucial for the establishment of immunological memory during a secondary immune response?

Memory B cells Signup and view all the answers

What is the role of regulatory T cells (TR cells) in the immune response?

To regulate and suppress immune responses Signup and view all the answers

What happens when B cells differentiate into plasma cells?

They begin producing large amounts of antibodies Signup and view all the answers

Study Notes

Activation of the Adaptive Immune Response

Antigen Presenting Cells (APCs) include macrophages, dendritic cells, and neutrophils, crucial for activating the adaptive immune response.
APCs phagocytize foreign pathogens and present their antigens to invoke an immune reaction.

Lymphocytes

Lymphocytes are white blood cells found in blood and the lymphatic system, primarily consisting of two types: T cells and B cells.
T cells kill pathogens and activate B cells; they are formed in the bone marrow and mature in the thymus.
B cells produce antibodies and form memory cells, originating and maturing in the bone marrow.

T Lymphocytes and Cell-Mediated Immunity

T cells originate in the bone marrow and mature in the thymus where they undergo clonal deletion.
Mature T cells circulate in the blood and lymphatic tissues; clonal deletion ensures self-tolerance by eliminating cells that react to self-antigens.
Central tolerance occurs during maturation; peripheral tolerance refers to clonal deletion of immature cells responding to self-antigens.

Steps of T-Cell Action

Neutrophils and macrophages phagocytose pathogens and present antigens to T-helper cells (TH cells).
Activation of TH cells leads to stimulation of cytotoxic T cells (TC), memory T cells, and B cells; they produce cytokines to enhance immune response.
TC cells directly kill infected cells, while TM cells provide long-term immunity.
Regulatory T cells (TR) prevent autoimmunity by regulating the immune response.
B cells synthesize antibodies targeted against specific pathogens.

Mechanism of Cytotoxic T Cells

TC cells induce apoptosis in virus-infected cells through several mechanisms.
TC cells bind to infected cells via MHC molecules, producing perforins that create pores in target cell membranes.
Granzyme enzymes enter through these pores; granzyme A poisons the cell, and granzyme B destroys it.
Apoptosis is initiated by the binding of the TC cell's Fas ligand to the Fas receptor on the target cell.
Interferons are released to inhibit viral replication and enhance the immune response in neighboring cells.
Antibodies act on released viruses during and after the apoptotic event, opsonizing them to prevent further infection.

B-Cells and Humoral Immunity

Each B cell is specific to a unique antigen; TH cells activate these specific B cells.
Activated B cells undergo clonal expansion, rapidly proliferating to fight the infection.
During clonal expansion, B cells differentiate into plasma cells or memory B cells.
Plasma B cells produce antibodies during the primary immune response; they are short-lived.
Memory B cells provide rapid antibody production during secondary infections, underpinning immunological memory, which facilitates faster and more effective responses upon re-exposure to the same pathogen.
Humoral immunity relies on antibodies found in bloodstream and lymphatic fluid, central to the body’s defense mechanism.

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Description

This quiz covers the activation of the adaptive immune response, focusing on Antigen Presenting Cells (APCs), lymphocytes including T cells and B cells, and their roles in immunity. Understand how these cells work together to defend against pathogens and the processes of self-tolerance in T cell maturation.