Cell-Mediated Immunity: T Cells and Immune Response
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Questions and Answers

Which of the following is a characteristic shared by both T cells and B cells?

  • Requirement for antigen processing by APCs
  • Immunoglobulin-based receptors
  • Direct recognition of antigens in their native form
  • Specificity for antigens, including immunologic memory (correct)

Which of the following is primarily associated with cell-mediated immunity, rather than antibody-mediated immunity?

  • Neutralization of viruses in the bloodstream
  • Response to toxins and allergens
  • Defense against intracellular infections (correct)
  • Response to extracellular pathogens

What do B cells recognize?

  • Epitopes found on complete, unprocessed antigens (correct)
  • Modified lipids presented by APCs
  • Glycolipids presented by CD1 molecules
  • Peptides bound to MHC molecules

Which of the following is a key requirement for T cell recognition of an antigen?

<p>Association of the antigen with an MHC molecule on an APC (D)</p> Signup and view all the answers

The T cell receptor (TCR) is structurally most similar to which part of an antibody molecule?

<p>The Fab region (A)</p> Signup and view all the answers

Which of the following best describes how B cells recognize antigens?

<p>Recognizes antigens in their native conformation in fluids (B)</p> Signup and view all the answers

Which surface molecule is found on all T cells?

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

What percentage of T cells express CD4?

<p>65% (B)</p> Signup and view all the answers

What is the first step in T cell development?

<p>Migration from the bone marrow to the thymus (A)</p> Signup and view all the answers

Which of the following characteristics describes a 'double-negative' thymocyte?

<p>Expresses neither CD4 nor CD8 (A)</p> Signup and view all the answers

What is the consequence of a thymocyte failing to recognize self-MHC during positive selection?

<p>Apoptosis(cell death) (D)</p> Signup and view all the answers

Where does negative selection of T cells primarily occur?

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

What process does T cell negative selection accomplish?

<p>Deleting autoreactive cells and inducing tolerance (D)</p> Signup and view all the answers

What is the fate of single-positive T cells that do not encounter their cognate antigen in the periphery?

<p>They die within a few weeks (B)</p> Signup and view all the answers

Which of the following is most accurate regarding the % composition of the T cell population?

<p>The majority of T cells are CD4+ (B)</p> Signup and view all the answers

Which of the following is comparable to the hypervariable loops of the V domain in antibodies?

<p>Complementarity Determining Regions (CDRs) (C)</p> Signup and view all the answers

What happens to TCR diversity after an antigen is encountered?

<p>TCR diversity remains the same it does doesn't continue to diversify (A)</p> Signup and view all the answers

What role does the T cell receptor (TCR) itself play in initiating effector function?

<p>The TCR has no direct effector function itself (C)</p> Signup and view all the answers

Which of the following molecules is a key component of the T-cell receptor complex and is involved in signal transduction?

<p>CD3 (A)</p> Signup and view all the answers

Co-stimulatory signals, such as the interaction between CD28 and B7, are crucial for T cell activation. What is the primary reason for this?

<p>They are required for cytokine production and sustained T cell response (B)</p> Signup and view all the answers

What happens to T cells if they receive a signal through their antigen receptor, but do not receive a co-stimulatory signal?

<p>They become anergic, or unresponsive, to the antigen. (C)</p> Signup and view all the answers

What are the steps required for a T cell to become activated?

<p>MHC-antigen presentation and co-stimulation (C)</p> Signup and view all the answers

Superantigens differ from conventional antigens because they:

<p>Bind directly to the T cell receptor and MHC molecules outside the peptide-binding groove (A)</p> Signup and view all the answers

How do superantigens lead to a cytokine storm?

<p>By simultaneously cross-linking MHC class II and the TCR of many T cells (C)</p> Signup and view all the answers

Identify a later stage pathology associated with superantigen exposure.

<p>Immunosuppression (A)</p> Signup and view all the answers

Which best describes the function of a T Cell checkpoint?

<p>Modulate T cell response and prevent autoimmunity (D)</p> Signup and view all the answers

Which of the following is a similarity between cell-mediated immunity and antibody-mediated immunity?

<p>Memory (A)</p> Signup and view all the answers

All of the following apply to antibody-mediated immunity, EXCEPT:

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

All of the following apply to cell-mediated immunity, EXCEPT:

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

After T cells graduate, they mainly become.

<p>Mature Naive CD4+ and CD8+ (B)</p> Signup and view all the answers

What is the function of cytotoxic lymphocytes (CTL) or T Killers:

<p>Can kill specific target cells: virus infected, tumor, etc (D)</p> Signup and view all the answers

Which of the following would be something that T helpers would regulate?

<p>All of the above (D)</p> Signup and view all the answers

What is the role of regulatory T cells?

<p>Promotes mucosal immunity (B)</p> Signup and view all the answers

What do TH1 Cells produce?

<p>IL-12, IL-2 (A)</p> Signup and view all the answers

What kind of cells do TH2 cells stimulate?

<p>Stimulate anti-parasitic cells (B)</p> Signup and view all the answers

The following are key to what types of responses?:TH1--cell mediated (antiviral)

<p>The responses to viral antigens (D)</p> Signup and view all the answers

The following are key to what types of responses?:TH2-humoral (antiparasitic)

<p>Reactions against parasitic response (A)</p> Signup and view all the answers

Treg cells contribute to what types of immunity?

<p>Mucosal. (A)</p> Signup and view all the answers

When classifying TFH cells; which of the following statements is true?

<p>B Cell helper (C)</p> Signup and view all the answers

All of the different types of T helper cells inhibit the functions of one another. What is the main reason?

<p>To coordinate the different types of immune response (B)</p> Signup and view all the answers

Killing is not immunogen-specific nor MHC-restricted for which cell?

<p>Natural Killer Cells (C)</p> Signup and view all the answers

Which of the following is a key distinction between how T cells and B cells recognize antigens?

<p>B cells recognize antigens in their native conformation, while T cells require processed antigens presented by MHC molecules. (B)</p> Signup and view all the answers

What is the structural relationship between T cell receptors (TCRs) and B cell receptors?

<p>TCRs are heterodimers analogous to the Fab region of an antibody, with variable and constant domains. (D)</p> Signup and view all the answers

Which of the following best describes the nature of epitopes recognized by T cells, compared to those recognized by B cells?

<p>T cells recognize epitopes derived from metabolized immunogens presented by MHC molecules, whereas B cells bind epitopes on complete immunogens. (B)</p> Signup and view all the answers

Which of the following surface molecules is present on all T cells and is directly involved in signal transduction?

<p>CD3 (A)</p> Signup and view all the answers

During T cell development in the thymus, what is the significance of 'positive selection'?

<p>It promotes the survival of T cells that can recognize self-MHC molecules. (A)</p> Signup and view all the answers

Which event triggers 'negative selection' of T cells in the thymus?

<p>Strong interaction with self-antigens presented on MHC molecules (B)</p> Signup and view all the answers

What is the defining characteristic of double-negative (DN) thymocytes in T cell development?

<p>Lack of expression of both CD4 and CD8. (C)</p> Signup and view all the answers

What is the immediate outcome for T cells in the periphery if they are antigen-reactive but do not encounter their cognate antigen presented by an APC?

<p>They undergo apoptosis due to lack of stimulation. (D)</p> Signup and view all the answers

The T cell receptor (TCR) genes undergo V(D)J recombination to generate diversity. How does TCR diversity change after an antigen is encountered?

<p>TCR diversity decreases as T cells with high affinity for the antigen are selected and expanded. (C)</p> Signup and view all the answers

Which of the following best explains the role of CD28-B7 interaction in T cell activation?

<p>It delivers a co-stimulatory signal that enhances T cell activation and survival. (D)</p> Signup and view all the answers

What is the consequence if a T cell receives a signal through its antigen receptor but does not receive a co-stimulatory signal?

<p>The T cell enters a state of anergy and becomes unresponsive to future stimulation. (C)</p> Signup and view all the answers

How do superantigens differ from conventional antigens in their interaction with T cells and antigen-presenting cells (APCs)?

<p>Superantigens bind to the MHC and T cell receptor outside of the peptide-binding groove, activating a large proportion of T cells, while conventional antigens bind within the groove, activating only T cells with a specific receptor. (D)</p> Signup and view all the answers

How do superantigens contribute to a cytokine storm?

<p>By activating a large proportion of T cells, leading to the massive release of cytokines. (A)</p> Signup and view all the answers

What is a later-stage pathology associated with superantigen exposure?

<p>Anergy or apoptosis of T cells (B)</p> Signup and view all the answers

Which of the following molecular interactions is essential for initiating T cell activation?

<p>Interaction between the T cell receptor and an antigen presented by an MHC molecule on an antigen-presenting cell (B)</p> Signup and view all the answers

Which characteristic distinguishes cell-mediated immunity from antibody-mediated immunity?

<p>Cell-mediated involves cytotoxic T lymphocytes. (C)</p> Signup and view all the answers

What is the primary function of cytotoxic T lymphocytes (CTLs)?

<p>Directly killing infected or cancerous cells. (B)</p> Signup and view all the answers

What determines whether a T cell expresses CD4 or CD8?

<p>The ability of the T cell receptor to bind to MHC class I or MHC class II molecules. (C)</p> Signup and view all the answers

What is the role of T helper cells in adaptive immune responses?

<p>Secreting cytokines that regulate and coordinate the activities of other immune cells. (B)</p> Signup and view all the answers

What is the function of regulatory T cells (Tregs)?

<p>Suppressing the activity of other immune cells and maintaining immune tolerance. (D)</p> Signup and view all the answers

What is a primary function of TH1 helper T cells?

<p>Activating macrophages to enhance intracellular killing. (D)</p> Signup and view all the answers

With which type of immune response are TH2 cells primarily associated?

<p>Humoral immunity against parasitic infections. (A)</p> Signup and view all the answers

What is a key characteristic of follicular helper T cells (TFH cells)?

<p>They migrate to lymphoid follicles to help B cells. (C)</p> Signup and view all the answers

The interplay of different T helper cell subsets typically involves mutual inhibition. What is the primary reason for this?

<p>To prevent any one type of immune response from becoming too dominant. (C)</p> Signup and view all the answers

What is one key difference between gamma-delta (γδ) T cells and alpha-beta (αβ) T cells?

<p>γδ T cells are not restricted by CD4 or CD8 co-receptors. (B)</p> Signup and view all the answers

What is one defining characteristic of gamma-delta (γδ) T cells?

<p>They recognize non-peptide antigens and do not require MHC presentation for activation. (D)</p> Signup and view all the answers

What distinguishes Natural Killer (NK) cells from cytotoxic T lymphocytes (CTLs)?

<p>NK cells kill target cells by detecting loss of MHC class I expression, and do not require prior sensitization or immunogen-specific recognition. CTLs, by contrast, recognize specific antigens presented by MHC. (C)</p> Signup and view all the answers

What is antibody-dependent cell-mediated cytotoxicity (ADCC)?

<p>A mechanism by which NK cells are activated to kill antibody-coated target cells. (B)</p> Signup and view all the answers

How is antigen processing required for MHC class II presentation?

<p>Proteins from the lysosome need to be chopped up. (D)</p> Signup and view all the answers

How do immune cells interact at a T Cell Checkpoint?

<p>APC delivers signals that cause the T cell to go into an autotolerant stage. (A)</p> Signup and view all the answers

For adaptive Immunities there are several different types of T helpers. What is the primary function of treg cells?

<p>Key role in tolerance and producing primarily immunosuppressive cytokines. (C)</p> Signup and view all the answers

Which of the following is a key distinction between T cell and B cell epitopes in infectious organisms?

<p>B cells bind epitopes on complete immunogens as they normally exist. (D)</p> Signup and view all the answers

What is the significance of an antigen-presenting cell (APC) in T cell recognition?

<p>APC processes and presents antigens in association with MHC molecules for T cell recognition. (C)</p> Signup and view all the answers

How does the T cell receptor (TCR) differ structurally from the B cell receptor (BCR)?

<p>The BCR is an immunoglobulin molecule whereas the TCR is not, though it shares analogous structural features. (C)</p> Signup and view all the answers

What role does the CD3 molecule play in T cell activation?

<p>CD3 is a molecule that binds to the T cell receptor complex and is crucial for signal transduction. (A)</p> Signup and view all the answers

What is the meaning of the term 'double-positive' in the context of T cell development in the thymus?

<p>The thymocyte expresses both CD4 and CD8 co-receptors. (D)</p> Signup and view all the answers

What is the primary consequence of T cells failing positive selection in the thymus?

<p>Failure to recognize self-MHC molecules, leading to cell death by apoptosis. (B)</p> Signup and view all the answers

How does negative selection in T cell development prevent autoimmunity?

<p>By inducing tolerance to self-antigens through the deletion of autoreactive T cell clones. (D)</p> Signup and view all the answers

What is the fate of a mature T cell that is antigen-reactive but does not encounter its cognate antigen in the periphery?

<p>It dies within several weeks due to lack of stimulation. (D)</p> Signup and view all the answers

How do superantigens differ from conventional antigens in terms of T cell activation?

<p>Superantigens bind outside the normal peptide-binding groove of the TCR and MHC, activating a large proportion of T cells. (B)</p> Signup and view all the answers

Which of the following is a key characteristic of T helper cells?

<p>Regulating immune responses through the production of cytokines. (A)</p> Signup and view all the answers

Regulatory T cells (Tregs) are crucial for maintaining immune homeostasis. How do Tregs primarily exert their function?

<p>By releasing immunosuppressive cytokines and direct cell-cell contact to suppress the activity of other immune cells. (A)</p> Signup and view all the answers

How do TH1 cells contribute to cell-mediated immunity?

<p>By activating macrophages and promoting intracellular immunity against viral infections. (B)</p> Signup and view all the answers

Which type of immune response is primarily associated with TH2 cells?

<p>Extracellular immunity against parasites and allergens. (B)</p> Signup and view all the answers

Follicular helper T cells (TFH cells) play a critical role in which of the following processes?

<p>Enhancing B cell antibody production in lymphoid follicles. (C)</p> Signup and view all the answers

What is the main reason why different T helper cell subsets (TH1, TH2, Tregs etc.) inhibit each other's functions?

<p>To concentrate the immune response to a specific type of pathogen and prevent a chaotic immune response. (A)</p> Signup and view all the answers

What is one way that gamma-delta (γδ) T cells differ from alpha-beta (αβ) T cells?

<p>γδ T cells do not require antigen processing or presentation by MHC molecules, where αβ T cells do require it. (D)</p> Signup and view all the answers

Which characteristic distinguishes Natural Killer (NK) cells from cytotoxic T lymphocytes (CTLs)?

<p>NK cells do not require prior sensitization, killing cells that lack MHC class I molecules or display stress ligands, whereas CTLs require antigen presentation. (A)</p> Signup and view all the answers

What is the mechanism of antibody-dependent cell-mediated cytotoxicity (ADCC)?

<p>A process where NK cells or other immune cells bind to antibody-coated target cells, leading to their destruction. (A)</p> Signup and view all the answers

For MHC class II presentation, how is the antigen typically processed?

<p>Antigens internalized into endosomes are degraded into peptides, which are then loaded onto MHC class II molecules. (C)</p> Signup and view all the answers

What is the general purpose of a T Cell Checkpoint in cancer immunity?

<p>To regulate T cell responses and prevent excessive immune activation or autoimmunity. (C)</p> Signup and view all the answers

Flashcards

Cell-mediated Immunity

Immunity against intracellular pathogens mediated by T cells.

Antibody-mediated Immunity

Targets molecular or extracellular antigens and infections.

B Cell Epitope Binding

B cells bind epitopes on complete immunogens as they exist.

T Cell Epitope Binding

T cells bind epitopes from metabolized immunogens associated with MHC.

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CD Markers

Surface molecules that identify and define T cell types & function.

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Double Negative Thymocytes

T cells that express neither CD4 nor CD8 during development.

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Double Positive Thymocytes

T cells that express both CD4 and CD8 during their development

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Positive Selection

Process where T cells recognizing self-MHC thrive during development.

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Negative Selection

Process where autoreactive T cells are eliminated during development.

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T Cell Receptor (TCR)

Heterodimer analogous to Ig Fab, recognizes processed immunogen with MHC.

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TCR

A protein heterodimer on T cells that recognizes processed immunogen

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Complementarity Determining Regions (CDR)

The hypervariable loops of the V domain, known as the CDR's.

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Classes of T-Cell Receptors

αβ or γδ

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T Cell Activation

Requires antigen-specific and co-stimulatory signal.

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T Cell Anergy

Describes the state of inactivity of the T cell

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Superantigen

Binds outside the TCR and MHC Class II, activating many T cells..

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Co-stimulation

Molecular interaction needed for T cell

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MHC Class I Presentation

MHC class I presents to CD8+ T killer cells.

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MHC Class II Presentation

MHC class II presents to CD4+ T helper cells.

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Antigen Processing

T killer cell antigen processing differs from T helper cell antigen processing

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T Cell Activation

T cell interaction with an APC requires antigen.

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APC interaction

Initial interaction not immunogen specific- adhesion molecules

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T Cells

Mature naive CD4+ and CD8+ are two types of?

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Definining Cytokines

Recognize defining cytokines.

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T Helper Cells

Cytokine factories that regulate B cells, T cells.

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T Cell Differentiation

TH0, TH1, TH2, Treg, TH17 and TFh

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T Regulatory Cells (Treg)

Produce primarily immunosuppressive cytokines.

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TH17 Cells

Involved in inflammatory responses.

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Lymphoid Follicle

Goes to lymphoid follicle after differentiation.

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Cytotoxic T Cells

Cytotoxic T cells travel to infected tissue.

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Virogenesis

Viral proteins synthesized in cytoplasm

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CD8+ T Cell Killing

CD8 kills through apoptotic pathways using granules, FasL.

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Cytotoxic T cells

Minor population in the peripheral blood.

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NK cells

Detect loss of MHC class I receptors- inhibited by MHC class

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Study Notes

  • Cell-mediated immunity focuses on the roles of T cells in immune responses.

Distinguishing Antibody-Mediated and Cell-Mediated Immunity

  • Antibody-mediated immunity targets molecular antigens and extracellular infections.
  • It deals with the extracellular phases of intracellular infections and some cellular antigens like those in transfusion reactions.
  • Cell-mediated immunity is effective against intracellular infections such as viruses.
  • It targets cellular antigens present in tumors and transplants and plays a role in contact dermatitis.
  • B cells recognize antigens as they natively exist in fluids like serum.
  • T cell recognition is an antigen processing that is restricted to the Major Histocompatibility Complex.

B Cell vs T Cell Epitopes

  • B cells bind epitopes on complete immunogens, including virulence factors, binding sites, and soluble toxins.
  • T cells recognize epitopes from metabolized immunogens.
  • T cell epitopes must be associated with the Major Histocompatibility Complex and presented on the surface of an antigen-presenting cell.
  • T cell responses can vary depending on the type of antigen-presenting cell and T cell.

T Cell vs B Cell Similarities

  • T and B cells share similarities in specificity and time-course including memory, and the need for helper cells.
  • Both cell-mediated and antibody-mediated immunity involve specific yet heterogeneous responses.
  • Primary and secondary responses, the requirement for help, and immunologic memory are features of both antibody and cell-mediated immunity.

Cellular Receptors

  • T and B cells are different with respect to their cellular receptors.
  • The B cell receptor is immunoglobulin.
  • The T cell receptor is not immunoglobulin, but is analogous to it.

Key Objectives in Understanding Cell-Mediated Immunity

  • Contrasting characteristics of T cell antigens versus B cell antigens.
  • Understanding how B cells recognize antigens compared to T cells.
  • Describing the basic structure of T cell receptors compared to B cell receptors.
  • Defining surface molecules, known as CD markers, on mature T cells and their functions.
  • Summarizing negative and positive selection processes during T cell development.
  • Understanding "double negative" and "double positive" terms in T cell development.

T Cell Types

  • B cells are fundamentally similar, though their immunoglobulin differs.
  • Helper cells (Th1, Th2, Treg, Th17) and effector cells (Cytotoxic, γδT) play roles in the immune response.

Differentiating T Cell Types

  • Differentiating T cell types involves defining specific surface molecules and their expression percentages.

Surface Molecules of T Cells

  • T cell receptor is present in 100% of T cells.
  • T cell receptor is a protein heterodimer for processed immunogen recognition.
  • CD3 is present in 100% of T cells.
  • CD3 is involved in signal transduction through a 6-protein molecule complex.
  • CD4 is identified in 65% of T cells for MHC Class II recognition.
  • CD8 is expressed in 35% of T cells for MHC Class I recognition.

T Cell Development

  • T cell development involves migration from bone marrow to the thymus, where they become thymocytes.

T Cell Development Stages

  • Double-negative thymocytes do not express CD4 and CD8, and T cell receptor expression begins.
  • Double-positive thymocytes express both CD4 and CD8 with increased T cell receptor expression.
  • Positive selection happens through T cell receptor stimulation and recognition of self-MHC molecules; lack of recognition leads to cell death
  • Negative selection involves immunogenic stimulation and deletion of autoreactive clones.

Selection Results

  • Single-positive cells emerge as antigen-reactive CD4 or CD8 cells.
  • T cells migrate to lymphoid tissues and die if not stimulated by an immunogen within several weeks.

T Cell Receptor (TCR)

  • The T cell receptor and antigen recognition process must be examined by comparing them to B cells and antibodies.
  • Studying the biochemistry of signals and signal transduction is not necessary
  • The TCR is a heterodimer, analogous to the Ig Fab fragment.
  • Each TCR complex includes CD3 molecules for signal transduction.

T Cell Receptor Structure and Function

  • The structure of the TCR analogous to Ig Fab is the alpha and beta chains.
  • The heterodimer is analogous to Ig Fab.
  • αβ T-cell receptors consist of an alpha chain (MW 45,000) plus a beta chain (MW 55,000), analogous to the light and heavy Ig chains.
  • Characteristics include variable and constant domains in each chain.
  • Va and Vb contribute to the antigen-binding site specific for the Ag-MHC complex which is monovalent and monospecific
  • TCRs are anchored by transmembrane proteins.

TCR Genes

  • TCR genes are analogous to light and heavy chain Ig genes, and V(D)J recombinase is involved.
  • The alpha chain has Vα segments.
  • The beta chain has Vβ, Dβ, and Jβ segments.
  • Hypervariable loops of the variable domain are known as CDRs
  • Mechanisms of diversity for the TCR before antigen stimulation are similar to Ig
  • Once an antigen is encountered, the TCR remains the same where it diversifies and does not continue to diversify like Ig.
  • Immunoglobulin diversifies to optimize both antigen binding and effector function.
  • The TCR itself doesn't have an effector function.

TCR Classes

  • There are two classes of T-cell receptors: αβ and γδ.

T Cell Receptor + MHC Binding

  • T cells are activated through antigen-specific signals and co-stimulatory signals.
  • Co-receptors bind Ig-like domains of MHC molecules.
  • CD8 T cells and CD4 T cells are activated through different signals.
  • Co-stimulation is required for T cell activation, anergy can be seen, which results in T cell inactivation and tolerance.

T Cell Activation

  • Anergy occurs with only one signal and no infection

T Cell Subtypes - MHC Molecules

  • Major Histocompatibility Complex molecules are involved in interactions between T helper/killer cells and antigen-presenting cells.
  • T killer cell antigen processing differs from T helper cell antigen processing.

Antigen Presentation

  • Antigen must be broken down to be presented correctly
  • MHC Class II involved in presenting to CD4+ T Helper cells
  • MHC Class I involved in presenting to CD8+ T killer cells
  • APC must undergo basic processes to activate a T cell.
  • Understanding T cell checkpoints is important in cancer immunity.

MHC I and II Presentation

  • The main difference is exogenous v endogenous proteins

Activating A T Cell

  • Antigen binds with MHC Class II protein on an epithelial cell.
  • First, initial interaction of Thelper cell antigen, which is not an intrinsic immunogen that binds to LFA-1-ICAM-1 proteins.
  • Then, APC activation results in cytokine production which effects APC and Therlper Cell
  • Later the TCR sees processed peptide antigen and co-stimulation

Naive T cells and Mature T cells

  • They come out of the thymus
  • Tho cells differentiate into T cells using activating cytokines; Interlukin 12, 2, and 4

Types of T Cells

  • Helper T cells are cytokine factories, factories
  • TH1 is mediated against antivirals and TH2 is humoral against antiparasitics
  • Cytotoxic lymphocytes (CTL) or T killers are for the tumors or cells infected with viruses and will primarily kill through apoptosis.

Additional T Helper Cells

  • Both TH 1 cells and TH 2 cells inhibit each other.

Functions of T Helper Cells

  • T helpers regulate many different cells like; B cells, Macrophages and Inflammatory Cells
  • CD4+ T cells which are MHC Class II

Activating T Helper Cells

  • TH 1 activates through cytokines that inhibit the TH 2 responses, and promotes cell mediated immunity.
  • TH 2 through which and activates B Cell by stimulate parasitic cells and humoral immunity with parasitic antigen

Additional Helper T Cells

  • There are many different types of T helper cells; T Reg that is primarily for mucosa and TH 17 for inflammation through the activation of a new profile.
  • T reg is not a T suppresser and releases Cytokines to support mucosal activity
  • TH 17 with Bacteria and TH 1 and TH 2 with cytokine

Lymphoid Follicle

  • TFH then go to lymphoid production through antigen to activate the B cells resulting in germinal center

Killer T Cells

  • They have MCH Class I proteins
  • They recognize antigen and kill it through activation and proliferation in the cytoplasm

Gamma Delta T Cells

  • Minor population in the peripheral blood and lymphocytes from thymic selection without CD4 or CD
  • They are slightly related to NK cells and oral tolerence
  • Do not need MHC components to function

Killer Cells

  • 10-15% are lymphocytes but not immunogen - specific to help with cell mediated functions
  • They kill the loss of protein receptors with the use of IL-02 receptors and help to create Fcy activation

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Explore cell-mediated immunity and the role of T cells in immune responses. Compare antibody-mediated and cell-mediated immunity, focusing on their targets and effectiveness against different types of infections. Understand the distinctions between B cell and T cell epitopes and their recognition mechanisms.

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