Adaptive Immune Response

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Questions and Answers

Why is the adaptive immune response considered more sophisticated than the innate immune response?

It can be activated within minutes of encountering a pathogen.
It relies solely on physical barriers to prevent pathogen entry.
It can generate immunological memory and targeted responses. (correct)
It uses a generalized response that is identical for all pathogens.

Which characteristic is unique to B cells that enables them to effectively combat pathogens?

Their role in activating cytotoxic T lymphocytes.
Their ability to directly phagocytose infected cells.
Their function as antigen-presenting cells to initiate T cell responses.
Their capacity to differentiate into plasma cells and produce specific antibodies. (correct)

What is the fundamental principle behind clonal selection in the context of an immune response?

Selective expansion of lymphocytes that recognize a specific antigen, creating a population of identical cells. (correct)
Random mutation of lymphocyte receptors to recognize any possible antigen.
Suppression of lymphocytes that react against self-antigens to prevent autoimmunity.
Indiscriminate activation of all lymphocytes regardless of antigen specificity to mount a broad immune response.

How do T cells and B cells differ in their maturation locations and primary mechanisms of immunity?

T cells mature in the thymus and mediate cell-mediated immunity, while B cells mature in the bone marrow and mediate humoral immunity. (B) Signup and view all the answers

What is the critical role of antigen-presenting cells (APCs) in initiating an adaptive immune response?

Presenting processed antigens to T cells to initiate an adaptive immune response. (A) Signup and view all the answers

How do Natural Killer (NK) cells distinguish between healthy cells and cells that are potentially harmful, such as virally infected or cancerous cells?

By detecting 'missing self' markers, such as the absence of normal surface proteins. (C) Signup and view all the answers

What is the primary role of regulatory T cells (Tregs) in maintaining immune homeostasis and preventing autoimmune reactions?

Suppressing immune responses after an infection to prevent autoimmune reactions and maintain system balance. (D) Signup and view all the answers

What initiates the classical complement pathway, leading to a cascade of protein activations that enhance pathogen elimination?

The binding of C1 to antibodies that are already bound to pathogens. (D) Signup and view all the answers

Why is IgA particularly important in mucosal immunity, and where is it predominantly found in the body?

It enhances pathogen elimination in mucosal membrane surfaces and is found in bodily secretions. (B) Signup and view all the answers

What distinguishes a secondary immune response from a primary immune response in terms of speed and magnitude?

The secondary response is faster and stronger because memory cells are already present from the primary exposure. (B) Signup and view all the answers

What is the essential function of Major Histocompatibility Complex (MHC) proteins in the context of adaptive immunity?

Presenting antigens to T cells, enabling recognition and response to foreign substances. (C) Signup and view all the answers

What are the two primary functions of lymph nodes within the lymphatic system?

Filtering lymph fluid to trap pathogens and housing immune cells for pathogen destruction. (A) Signup and view all the answers

How is lymph transported throughout the body?

Through muscular contractions and one-way valves that prevent backflow. (B) Signup and view all the answers

Which of the following characteristics distinguishes the innate immune system from the adaptive immune system?

The innate immune system responds rapidly but non-specifically, whereas the adaptive immune system responds slowly but with high specificity after an initial exposure (A) Signup and view all the answers

Considering the critical role of antibodies in adaptive immunity, what mechanism enables them to neutralize pathogens effectively?

Antibodies enhance phagocytosis by marking pathogens for destruction by macrophages and neutrophils. (A) Signup and view all the answers

In the context of clonal selection, what is the significance of the affinity between a lymphocyte receptor and its corresponding antigen for determining the strength and effectiveness of an immune response?

High affinity promotes stronger activation, proliferation, and differentiation of the lymphocyte clone, leading to a more effective immune response. (C) Signup and view all the answers

How does the maturation process and functional specificity of T cells in the thymus ensure that the body's immune system does not attack its own cells?

T cells undergo negative selection, where those that strongly recognize self-antigens are eliminated, preventing autoimmunity. (D) Signup and view all the answers

What role do dendritic cells, as a specific type of antigen-presenting cell (APC), play in initiating T cell responses against pathogens?

Dendritic cells present processed antigens on MHC molecules, enabling T cells to recognize and respond to the pathogen. (B) Signup and view all the answers

How does the mechanism by which natural killer (NK) cells recognize and eliminate target cells differ from that of cytotoxic T lymphocytes (CTLs)?

NK cells recognize cells lacking normal surface proteins or displaying stress signals, allowing them to eliminate a broader range of abnormal cells without prior sensitization. (D) Signup and view all the answers

Given that regulatory T cells (Tregs) play a crucial role in modulating immune responses, which molecular mechanisms do they employ to suppress the activity of other immune cells and prevent autoimmune reactions?

Tregs express CTLA-4, which inhibits T cell activation by binding to B7 molecules on antigen-presenting cells, and secrete suppressive cytokines like IL-10 and TGF-β. (B) Signup and view all the answers

Considering that the complement cascade enhances the immune response, through what three distinct mechanisms does the complement system eliminate pathogens and promote inflammation?

Opsonization to enhance phagocytosis, direct lysis of pathogens by forming membrane attack complexes (MAC), and recruitment of inflammatory cells through the production of chemotactic factors. (D) Signup and view all the answers

In the context of mucosal immunity, what unique structural and functional properties of IgA enable it to effectively neutralize pathogens and maintain immune homeostasis at mucosal surfaces?

IgA is secreted as a dimer, which allows it to bind to the polymeric immunoglobulin receptor (pIgR) for transcytosis across epithelial cells, neutralizing pathogens without causing inflammation. (A) Signup and view all the answers

When comparing primary and secondary immune responses, what immunological mechanisms account for the faster kinetics and enhanced magnitude observed during the secondary response?

The secondary response benefits from faster activation of memory cells which have already undergone affinity maturation; a process that improves their recognition of the antigen. (A) Signup and view all the answers

What are the two distinct classes of MHC molecules (MHC Class I and MHC Class II) and what is their respective role in presenting antigens to T cells and influencing immune responses?

MHC Class I presents endogenous antigens to CD8+ T cells, leading to the destruction of infected cells, while MHC Class II presents exogenous antigens to CD4+ T cells, activating them to coordinate immune responses. (A) Signup and view all the answers

Given the critical role of lymph nodes in initiating adaptive immune responses, what specialized structural features within the lymph nodes facilitate interactions between antigen-presenting cells, lymphocytes, and antigens?

Lymph nodes are encapsulated structures with distinct B cell follicles and T cell zones, facilitating antigen presentation, lymphocyte activation, and clonal expansion. (C) Signup and view all the answers

How do one-way valves and muscular contractions facilitate the transport of lymph throughout the body?

Muscular contractions push lymph through lymphatic vessels, and one-way valves prevent backflow, ensuring unidirectional movement. (B) Signup and view all the answers

Considering the complexities of immune responses, how does the phenomenon of immunological tolerance prevent the immune system from attacking the body's own tissues and causing autoimmune diseases?

Immunological tolerance involves deletion or inactivation of self-reactive lymphocytes through central and peripheral tolerance mechanisms. (D) Signup and view all the answers

What are the key differences between central and peripheral tolerance mechanisms in maintaining immunological self-tolerance?

Central tolerance is induced in the thymus and bone marrow through deletion or receptor editing of self-reactive lymphocytes, while peripheral tolerance involves mechanisms like anergy and suppression in peripheral tissues. (A) Signup and view all the answers

How does the process of affinity maturation contribute to the enhanced efficacy of antibody-mediated immunity during the course of an adaptive immune response?

B cells undergo somatic hypermutation which introduces mutations in the variable regions of antibody genes; B cells with higher-affinity antibodies are selectively promoted to survive and differentiate into antibody-secreting plasma cells. (D) Signup and view all the answers

In the context of immune responses to viral infections, what distinguishes the roles of neutralizing antibodies and cytotoxic T lymphocytes (CTLs) in controlling viral spread and eliminating infected cells?

Neutralizing antibodies opsonize extracellular virus particles preventing them from infecting new cells, while CTLs recognize and kill virus-infected cells by inducing apoptosis. (C) Signup and view all the answers

Considering the role of cytokines in regulating immune responses, how do pro-inflammatory and anti-inflammatory cytokines interact and communicate to maintain immune homeostasis?

Pro-inflammatory cytokines promote inflammation and immune cell activation to eliminate pathogens, while anti-inflammatory cytokines dampen these responses to prevent excessive tissue damage and autoimmunity. (C) Signup and view all the answers

How do memory T cells differ from naive T cells in terms of activation requirements and effector functions during a secondary encounter with a specific antigen?

Memory T cells are more easily activated, respond more rapidly, and mediate enhanced effector functions compared to treatment-naive T cells upon re-exposure to the same antigen. (A) Signup and view all the answers

How do disruptions or defects in the complement system contribute to the development of autoimmune and immune complex-mediated diseases?

Dysregulation of the complement system leads to unchecked inflammation, impaired clearance of immune complexes, and enhanced activation of self-reactive lymphocytes, contributing to autoimmune and immune complex-mediated diseases. (A) Signup and view all the answers

How does the process of somatic hypermutation contribute to the generation of antibody diversity and enhanced affinity during B cell development?

Somatic hypermutation induces random mutations in the variable regions of antibody genes, followed by selection of B cells producing antibodies with higher affinity for the antigen. (B) Signup and view all the answers

How do T helper (Th) cells coordinate and regulate adaptive immune responses through the secretion of cytokines, and what are the distinct roles of Th1, Th2, and Th17 subsets in shaping these responses?

Th1 cells promote cell-mediated immunity against intracellular pathogens, Th2 cells facilitate antibody-mediated immunity against extracellular pathogens, and Th17 cells enhance mucosal immunity and inflammation. (C) Signup and view all the answers

Considering the increasing prominence of immunotherapy in cancer treatment, what are the mechanisms by which immune checkpoint inhibitors, such as anti-CTLA-4 and anti-PD-1 antibodies, enhance anti-tumor immune responses?

Immune checkpoint inhibitors block inhibitory signals that suppress T cell activation, thus unleashing T cell-mediated killing of tumor cells. (B) Signup and view all the answers

Flashcards

Adaptive Response

An immune response that creates immunological memory and targeted responses.

Branches of Immunity

The two main branches of immunity are innate (first line of defense, such as skin barriers) and adaptive (targeted response with memory).

Antibody Producing Cells

B cells produce antibodies. They can differentiate into memory B cells and plasma cells that secrete specific antibodies.

Clonal Selection

Specific lymphocytes recognize an antigen and multiply to create many identical cells that fight that specific threat; important for immunity