Adaptive Immunity and Antigens Quiz

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Questions and Answers

What is the primary contribution of Louis Pasteur to the field of immunology?

  • Development of the side chain theory.
  • Pioneering the method of weakening pathogens for inoculation. (correct)
  • Discovery of antibodies and antigens.
  • Identifying the role of T cells in adaptive immunity.

Which scientist is credited with the development of the side chain theory of immunity?

  • Max Cooper
  • Paul Ehrlich (correct)
  • Jacques Miller
  • Louis Pasteur

What is the major contribution of Max Cooper to understanding adaptive immunity?

  • Discovery of the role of the Bursa in B cell maturation. (correct)
  • Identification of the process of genetic recombination for antibody proteins.
  • Discovery of the thymus and its role in T cell development.
  • Demonstration of the role of CD4 and CD8 in T cell activation.

What is the essential function of an epitope?

<p>To interact with the antigen-binding site of a B or T cell receptor. (A)</p> Signup and view all the answers

Which of these statements best describes the role of MHC molecules in T cell recognition?

<p>They process and present peptide antigens to T cell receptors. (B)</p> Signup and view all the answers

Which of the following is true regarding the clonal selection theory?

<p>An antigen selects and activates only the lymphocytes with receptors that can bind to it. (A)</p> Signup and view all the answers

Which of the following statements is correct about the structure of B cell receptors (BCRs)?

<p>They are made up of 2 heavy and 2 light polypeptide chains. (C)</p> Signup and view all the answers

What is the primary difference between B cell and T cell receptor recognition of antigens?

<p>B cell receptors only recognize native antigens, T cell receptors must be presented with processed antigens (B)</p> Signup and view all the answers

What is the significance of VDJ recombination in the immune system?

<p>It produces diverse antigen receptors that can recognize new and unique antigens. (D)</p> Signup and view all the answers

What is the function of CD4 and CD8 molecules in T cell activation?

<p>They stabilize the interaction of the T cell receptor with the MHC molecule. (D)</p> Signup and view all the answers

What is 'clonal deletion' in the context of lymphocyte development?

<p>The removal of lymphocytes that recognize self antigens. (B)</p> Signup and view all the answers

What is a main attribute of the secondary immune response compared to the primary immune response?

<p>It is faster and more robust due to the presence of memory cells. (A)</p> Signup and view all the answers

According to the content, in which location does B cell maturation occur in mammals?

<p>The medullary cavity of the bone marrow (A)</p> Signup and view all the answers

Which of the following does NOT describe the structure of T cell receptors?

<p>They are secreted molecules that circulate throughout the body. (A)</p> Signup and view all the answers

What did Tak Mak and Mark Davis discover about T-cell receptors?

<p>They discovered that the genes encoding the T-cell receptors. (B)</p> Signup and view all the answers

Flashcards

Adaptive Immunity

The ability of the immune system to recognize and target specific pathogens or foreign substances. It involves specialized cells and molecules that adapt over time to provide long-lasting immunity.

Vaccine

A weakened or inactive form of a pathogen that is used to induce an immune response without causing disease. It triggers the adaptive immune system to generate memory cells, providing immunity against future infections.

Clonal Selection Theory

A theory that explains how the immune system generates a diverse repertoire of antibodies and T cell receptors with unique specificities. It states that each lymphocyte has a single type of receptor, and when encountering its specific antigen, it is activated and clonally expands, resulting in a population of cells with the same specificity.

Antigen

Any substance that can generate an immune response, typically by binding to specific receptors on immune cells.

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Epitope

A specific portion of an antigen that is recognized by the immune system, particularly by antibodies or T cell receptors.

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T Cells

Specialized cells within the adaptive immune system that are responsible for recognizing and destroying specific pathogens or infected cells.

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B Cells

Specialized cells within the adaptive immune system responsible for generating antibodies, which are proteins that bind to specific antigens and help neutralize them.

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B Cell Receptors (BCRs)

Receptors found on the surface of B cells that recognize specific antigens. These receptors trigger the activation of B cells and the production of antibodies.

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T Cell Receptors (TCRs)

Receptors found on the surface of T cells that recognize specific antigens, but only when presented in conjunction with Major Histocompatibility Complex (MHC) molecules.

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V(D)J Recombination

A process by which B and T cell receptors are generated during lymphocyte development. It involves a series of gene rearrangements that create a diverse repertoire of receptors with unique specificities.

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Negative Selection

A process by which the immune system eliminates lymphocytes that recognize self-antigens, preventing autoimmunity. It occurs during lymphocyte development within the bone marrow for B cells and the thymus for T cells.

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Primary Immune Response

The first encounter with an antigen, leading to a relatively slow and weak immune response. It involves the activation and clonal expansion of specific T and B cells.

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Secondary Immune Response

The subsequent encounter with an antigen that has been previously encountered. It is characterized by a much faster and stronger response due to the presence of memory cells.

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Memory Cells

Cells produced during the initial encounter with an antigen that are responsible for the rapid and strong response during subsequent encounters with the same antigen.

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Study Notes

Adaptive Immunity

  • Louis Pasteur's work on culturing pathogens, passing them to animals, and then weakening them to create vaccines
  • Adaptive immunity involves lymphocytes (major cells) such as T and B lymphocytes
  • Thymus' role in T-lymphocyte development, discovered by Jacques Miller
  • Removal of the thymus eliminates adaptive immunity
  • B cells are responsible for antibody production
  • Removal of the Bursa of Fabricius in chickens eliminates antibody production
  • B cells mature in the bone marrow

Antigens and Epitopes

  • Antigens: substances that generate antibodies; recognized by B/T cell receptors
  • Epitopes are parts of antigens that bind with B/T cell receptors

B Cell Receptors and Antibodies

  • B cell receptors (BCRs) are membrane-bound or secreted forms of molecules with identical antigen specificity
  • They directly bind antigens, and coreceptors can translate signals
  • B-cells can make receptor and secreted antibodies (same specificity)

T Cell Receptors

  • T cells only recognize peptide antigens presented by MHC molecules
  • T cell receptors (TCRs) are cell-surface receptors
  • TCRs are made of two molecules: alpha and beta
  • TCR-MHC interaction is stabilized by CD4/CD8

Antigen Recognition by B and T Cells

  • B cell receptors (BCRs) and antibodies can recognize any type of antigen in any configuration
  • T cells recognize antigens only processed and presented by Antigen Presenting Cells (APCs) in the context of MHC molecules
  • Signal transduction by BCRs is enhanced by crosslinking

B/T Cell Specificity

  • Each B/T cell has a single receptor with unique specificity, each cell making the same type of receptor
  • B/T cells make receptors specific for one unique epitope (part of the antigen)
  • Repertoires of antigen specificities exist before cells encounter antigens

Clonal Selection Theory

  • Each lymphocyte has a unique receptor
  • Interaction with a foreign molecule activates corresponding lymphocytes
  • Effector cells have identical receptors to parent cells
  • Lymphocytes with receptors for self-molecules are deleted during development (preventing autoimmunity)

BCR and TCR Rearrangement

  • BCRs and TCRs are encoded by recombined genes
  • VDJ segments create antibodies and receptors
  • Recombination happens during lymphocyte development, creating the diverse repertoire of antigen specificities

Clonal Selection and Adaptive Immunity

  • Primary response: slow lag because T/B cells with the exact specificity are rare, thus needed to be clonally selected
  • Secondary response: faster response because many more T/B cells now have the same specificity after infection resolves itself.

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