Gamma Delta T Cells & Gingival Defense Mechanisms
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Questions and Answers

Which of the following is NOT a primary function of T helper cells in adaptive immunity?

  • Directly killing infected cells. (correct)
  • Releasing cytokines to stimulate B cells and plasma cells.
  • Suppressing adaptive immune responses by regulating antibody production.
  • Promoting inflammation through macrophage activation.

A patient's immune response is characterized by elevated levels of IL-17. Which T helper cell subset is most likely contributing to this observation?

  • Th17 cells (correct)
  • Th2 cells
  • Th1 cells
  • Treg cells

In an experiment, the interaction between a T helper cell and a B cell is blocked, preventing the T helper cell from delivering the co-stimulatory signal. What is the most likely outcome?

  • The B cell will differentiate into a plasma cell without isotype switching.
  • The B cell will become anergic and fail to respond to the antigen in the future. (correct)
  • The B cell will proliferate and produce antibodies against self-antigens.
  • The B cell will undergo apoptosis due to lack of survival signals.

Which of the following mechanisms is primarily used by T helper cells to activate macrophages?

<p>Release of cytokines like IFN-γ and direct cell-cell contact via CD40L-CD40 interaction. (B)</p> Signup and view all the answers

A researcher is studying a new therapeutic drug designed to enhance the adaptive immune response. The drug selectively stimulates the release of cytokines associated with Th2 cells. Which of the following outcomes would be the most expected result of this drug's activity?

<p>Increased antibody production and B cell activity. (B)</p> Signup and view all the answers

Gamma delta T cell subsets contribute to host defense through functional heterogenesis, enabling them to perform which of the following roles?

<p>Gingival homeostasis and immunosurveillance. (B)</p> Signup and view all the answers

Rete pegs are a structural component of the gingival epithelium. What is the PRIMARY function of rete pegs?

<p>Increase surface area between epithelium and connective tissue enhancing mechanical stability. (C)</p> Signup and view all the answers

The space between the junctional epithelium and the tooth surface contains gingival crevicular fluid (GCF). What is the PRIMARY role of immunoglobulins (IgM or IgG) present in GCF?

<p>Activating complement to promote bacterial cell death and phagocytosis. (C)</p> Signup and view all the answers

The gingival sulcus is lined by a specific type of epithelium. Which of the following accurately describes the sulcular epithelium?

<p>Nonkeratinized epithelium bounded apically by the junctional epithelium. (C)</p> Signup and view all the answers

Secretory IgA (sIgA) plays a critical role in maintaining gingival health. What is the MAIN function of sIgA on the gingival mucosal surfaces?

<p>Preventing bacterial adherence and neutralizing bacterial toxins. (A)</p> Signup and view all the answers

In the progression of periodontal disease, the initial lesion is characterized by specific changes. What is a key feature of the initial lesion stage (24-48 hours)?

<p>Localized to gingival sulcus with perivascular collagen loss. (D)</p> Signup and view all the answers

The early lesion (gingivitis) stage of periodontal disease is characterized by which of the following changes in the gingival tissues?

<p>Localized proliferation of junctional and sulcular epithelium with some collagen loss. (B)</p> Signup and view all the answers

The advanced lesion in periodontitis is marked by several key pathological events. Which of the following BEST describes the defining characteristics of an advanced lesion?

<p>Pocket formation and loss of attachment (A)</p> Signup and view all the answers

The complement system, a crucial part of innate immunity, comprises approximately how many proteins that enhance the ability of antibodies and phagocytic cells to clear microbes and damaged cells?

<p>20 (C)</p> Signup and view all the answers

Which of the following is NOT a pathway through which the complement system can be activated?

<p>Interferon pathway, induced by viral infections (A)</p> Signup and view all the answers

After activation of the complement cascade, C3 convertase cleaves C3 into C3a and C3b. What is the primary role of C3a?

<p>Mediation of inflammation and phagocyte recruitment (D)</p> Signup and view all the answers

Following the activation of complement component C3b, a cascade involving C5b, C6, C7, C8, and C9 is initiated. What is the primary outcome of this cascade?

<p>Formation of the membrane-attack complex (MAC) (B)</p> Signup and view all the answers

Which of the following best describes the primary function of neutrophils?

<p>Phagocytosis and bactericidal mechanisms (A)</p> Signup and view all the answers

During neutrophil migration into infected tissues, which receptor-ligand interaction is primarily responsible for the tight binding stage?

<p>ICAM-1 receptor and LFA-1 receptor (D)</p> Signup and view all the answers

Macrophages play a dual role in the immune response. Besides phagocytosis and bactericidal activity, what other crucial function do they perform?

<p>Presenting antigens to T cells to initiate adaptive immunity (D)</p> Signup and view all the answers

Toll-like receptors (TLRs) are a class of pattern recognition receptors. Which of the following cell types does NOT typically express TLRs?

<p>Neurons (C)</p> Signup and view all the answers

Which Toll-like receptor (TLR) primarily recognizes lipopolysaccharide (LPS), a major component of Gram-negative bacteria?

<p>TLR4 (B)</p> Signup and view all the answers

Intracellular TLRs recognize nucleic acids derived from pathogens. Which of the following TLRs is located intracellularly and recognizes double-stranded RNA (dsRNA)?

<p>TLR3 (D)</p> Signup and view all the answers

Cytokines are crucial for cell communication in the immune system. What is the primary function of cytokines?

<p>Mediating communication between immune and non-immune cells (B)</p> Signup and view all the answers

Interleukin-1beta (IL-1β) is a potent cytokine with both local and systemic effects. Which of the following is primarily a systemic effect of IL-1β?

<p>Fever (C)</p> Signup and view all the answers

Tumor necrosis factor-alpha (TNF-α) mediates diverse effects during inflammation. What is a key local effect of TNF-α?

<p>Increased vascular permeability (B)</p> Signup and view all the answers

Interleukin-6 (IL-6) is a pleiotropic cytokine involved in both inflammation and the acute phase response. Which of the following is a key systemic effect of IL-6?

<p>Induction of acute-phase protein production (A)</p> Signup and view all the answers

Antibodies play a critical role in protecting the host through various mechanisms. Which of the following describes the process of opsonization?

<p>Tagging pathogens for phagocytosis (A)</p> Signup and view all the answers

Flashcards

T helper cells

Immune cells that promote antibody production and activate other immune cells.

Role of Th1 cells

They activate macrophages and promote inflammation in adaptive immunity.

Role of Th2 cells

They release cytokines that promote B cells and plasma cells activation.

Role of Th17 cells

They produce IL-17, enhancing neutrophil function and promoting antibody production.

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Treg cells

Regulatory T cells that suppress the adaptive immune response and control antibody production.

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Gamma delta T cell subsets

Subsets of T cells involved in host defense, allowing for functional heterogenesis.

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Immunosurveillance

The process by which the immune system monitors for signs of infection or disease.

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Gingival homeostasis

The balance and health of the gingival tissues in the oral environment.

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Rete pegs

Structures that increase the contact area between epithelium and connective tissue for stability.

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Gingival crevicular fluid (GCF)

Fluid in the space between the junctional epithelium and tooth, containing immune elements.

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Sulcular epithelium

The nonkeratinized epithelium lining the gingival sulcus.

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Secretory IgA (sIgA)

An antibody that prevents bacterial adherence and neutralizes toxins at mucosal surfaces.

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Stages of periodontal lesions

Four stages: initial, early, established, and advanced; each with specific changes.

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Host-Microbial Interaction

Balance between the host and microorganisms, crucial for health.

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Complement System

A group of proteins that enhances immune reactions.

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Membrane Attack Complex (MAC)

Structure formed by complement proteins that lyses pathogens.

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Complement Activation Pathways

Ways to activate the complement system: classical, lectin, and alternative.

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C3 Convertase

An enzyme complex that activates other complement proteins.

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Inflammatory Mediators

C3a and C5a that promote inflammation and recruit phagocytes.

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Neutrophil Functions

Primarily involved in phagocytosis and activating bactericidal mechanisms.

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Neutrophil Migration Stages

The process includes rolling, tight binding, diapedesis, and migration.

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Macrophage Roles

Involved in phagocytosis and antigen presentation.

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Toll-Like Receptors (TLRs)

Receptors that recognize pathogens and activate immune responses.

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Cytokines

Signaling proteins that mediate and regulate immunity and inflammation.

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Local Effects of IL-1beta

Activates endothelium, lymphocytes, and causes tissue destruction.

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Systemic Effects of TNF-alpha

Causes fever, bone resorption, and synergizes with other cytokines.

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Antibody Roles

Neutralization, opsonization, and complement activation to protect host.

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Humoral Immunity Cells

B cells and plasma cells act in humoral immune response.

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Study Notes

Gamma Delta T Cell Subsets in Host Defense

  • Gamma delta T cells exhibit "functional heterogenesis," meaning they play diverse roles in host defense.
  • These roles include immunosurveillance and gingival homeostasis.

Diagram of Gingival Structure

  • (Diagram Description needed. Please provide the diagram.)*

Rete Pegs and Gingival Epithelium

  • Rete pegs increase the surface area between epithelium and connective tissue, enhancing mechanical stability.

Junctional Epithelium and GCF

  • The space between the junctional epithelium and tooth contains gingival crevicular fluid (GCF).
  • GCF contains immunoglobulins (IgM, IgG) and neutrophils.
  • IgM or IgG in GCF activate complement, leading to bacterial cell death and promoting phagocytosis.

Sulcular Epithelium

  • The gingival sulcus is lined by the sulcular epithelium, which is non-keratinized.
  • It's situated apically to the junctional epithelium and connects to the oral cavity at the free gingival margin.

sIgA and Gingival Mucosal Surfaces

  • Secretory IgA (sIgA) on gingival surfaces prevents bacterial adherence and neutralizes bacterial toxins.

Stages of Periodontitis Lesions

  • Initial lesion (24-48 hours): Localized to the gingival sulcus and periodontal tissue; some perivascular collagen loss occurs.
  • Early lesion (gingivitis, 4-7 days): Localized proliferation of junctional and sulcular epithelium; some collagen loss occurs beneath the epithelium, yet no loss of attachment (LOA).
  • Established lesion (2-3 weeks): Further proliferation of junctional and sulcular epithelium, more collagen loss in gingiva, still no LOA.
  • Advanced lesion (LOA): Pocket formation, loss of attachment (LOA), collagen destruction in the periodontal ligament and bone loss. An imbalance between host and microbes drives this stage from a successful defense to destructive pathology. A reparative, fibrotic response becomes more evident over time.

Complement System

  • Complement is a group of roughly 20 proteins.
  • Complement activation leads to the formation of a membrane attack complex (MAC) that creates pores in bacterial membranes leading to bacterial cell death.
  • A smaller complement fragment triggers an inflammatory response.
  • Three pathways activate complement: classical, lectin and alternative.

Complement Activation and Functions

  • Complement activation (C3 convertase stage) leads to the production of several fragments with various functions.
  • C3a and C5a are peptide mediators triggering inflammation and phagocyte recruitment.
  • C3b opsonizes pathogens, promotes phagocytosis, and removes immune complexes.
  • C5b-C9 are components of the MAC, directly causing pathogen lysis.

Neutrophil Function

  • Neutrophils perform phagocytosis and activate bactericidal mechanisms.
  • They migrate into tissues via steps like rolling adhesion, tight adhesion, diapedesis and motility.

Macrophage Function

  • Macrophages carry out phagocytosis, activate bactericidal mechanisms, and present antigens to T cells.
  • This promotes adaptive immune responses.

Toll-like Receptors (TLRs)

  • TLRs are present on immune cells, epithelial cells, PMNs, macrophages and dendritic cells.
  • TLR4 and TLR5 recognize gram-negative organisms.
  • TLR2 and TLR5 recognize gram-positive organisms.
  • Surface TLRs are typically TLR-6, TLR-2, TLR-5, and TLR-4; intracellular TLRs are usually TLR-3, TLR-7, and TLR-9.

Cytokines

  • Cytokines are crucial for communication between immune and non-immune cells.

Cytokine Effects

Local and systemic effects of various cytokines are described.

Immune Cell Types and Activities

  • Different cell types mediate humoral (antibodies) and cell-mediated (T cells) immune responses.
  • Antibodies contribute to host protection through neutralization, opsonization and complement activation.
  • T helper cells (Th1, Th2, Th17, Treg) are crucial for activating other immune cells.
  • The mechanisms of T helper cell activation (of B cells and macrophages) are given.

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Description

Explore the role of gamma delta T cells in host defense, focusing on immunosurveillance and gingival homeostasis. Learn about rete pegs, junctional epithelium, gingival crevicular fluid, and sulcular epithelium and their importance to immunity. Understand the structure and function of gingival tissues.

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