Podcast
Questions and Answers
What is the composition of the antigen binding site formed by B cell receptors?
What is the composition of the antigen binding site formed by B cell receptors?
- One variable and one constant domain
- Two variable regions from heavy and light chains (correct)
- Three constant domains from heavy chains
- Only heavy chain variable regions
Which step in B cell maturation involves the expression of the pre-BCR?
Which step in B cell maturation involves the expression of the pre-BCR?
- Mature B cell
- Pre-B cell (correct)
- Immature B cell
- Pro-B cell
What type of B cells undergo positive selection?
What type of B cells undergo positive selection?
- B cells that have not rearranged their heavy chain locus
- B cells with low-affinity receptors
- B cells expressing functional Ig molecules (correct)
- Self-reactive B cells
What occurs during negative selection of B cells?
What occurs during negative selection of B cells?
What characterizes follicular B cells?
What characterizes follicular B cells?
Which Ig molecules do mature B cells express as antigen receptors?
Which Ig molecules do mature B cells express as antigen receptors?
What is the main outcome of positive selection in the thymus?
What is the main outcome of positive selection in the thymus?
What is a defining feature of marginal zone B cells?
What is a defining feature of marginal zone B cells?
What is the primary function of plasma cells derived from activated mature B cells?
What is the primary function of plasma cells derived from activated mature B cells?
What occurs during negative selection of T cells?
What occurs during negative selection of T cells?
Which chains form the T cell Antigen Receptor (TCR)?
Which chains form the T cell Antigen Receptor (TCR)?
Which of the following cells are considered professional antigen presenting cells (APCs)?
Which of the following cells are considered professional antigen presenting cells (APCs)?
What is a distinguishing feature of MHC class I molecules?
What is a distinguishing feature of MHC class I molecules?
What is the role of CD3 in T cell activation?
What is the role of CD3 in T cell activation?
What is a feature of the B cell Antigen Receptor (BCR)?
What is a feature of the B cell Antigen Receptor (BCR)?
What components are involved in the structure of MHC class II molecules?
What components are involved in the structure of MHC class II molecules?
What distinguishes the light chains in B cell Antigen Receptors (BCRs)?
What distinguishes the light chains in B cell Antigen Receptors (BCRs)?
In the endocytic pathway for MHC class II antigen processing, where are exogenous antigens degraded?
In the endocytic pathway for MHC class II antigen processing, where are exogenous antigens degraded?
Which type of T cell interacts with MHC class I molecules?
Which type of T cell interacts with MHC class I molecules?
How do immature T cells differentiate into CD4+ or CD8+ T cells?
How do immature T cells differentiate into CD4+ or CD8+ T cells?
Which statement best describes the peptide binding site of MHC class I molecules?
Which statement best describes the peptide binding site of MHC class I molecules?
What ensures the stability of the T cell receptor during activation?
What ensures the stability of the T cell receptor during activation?
What type of antigens do MHC class II molecules present?
What type of antigens do MHC class II molecules present?
What is the primary processing machinery used for MHC class II antigen presentation?
What is the primary processing machinery used for MHC class II antigen presentation?
Which of the following molecules assists in the structure of MHC class I?
Which of the following molecules assists in the structure of MHC class I?
What type of cells present antigens through MHC class I?
What type of cells present antigens through MHC class I?
Which pathway is responsible for the presentation of peptides derived from cytosolic proteins?
Which pathway is responsible for the presentation of peptides derived from cytosolic proteins?
Which of the following best describes the antigen source for MHC class I presentation?
Which of the following best describes the antigen source for MHC class I presentation?
Which T cell type requires the presence of MHC class II molecules to recognize foreign peptides?
Which T cell type requires the presence of MHC class II molecules to recognize foreign peptides?
In which type of antigen processing pathway does MHC class II play a role?
In which type of antigen processing pathway does MHC class II play a role?
What is the major source of antigen for MHC class I presentation?
What is the major source of antigen for MHC class I presentation?
Which statement about MHC/T cell interactions is true?
Which statement about MHC/T cell interactions is true?
What is a primary function of CD4 T helper cells?
What is a primary function of CD4 T helper cells?
Which of the following best describes the role of B7 in T cell activation?
Which of the following best describes the role of B7 in T cell activation?
What is the end result of T cell activation?
What is the end result of T cell activation?
Which subset of T cells is involved in the early immune response by differentiating from naive T0 cells?
Which subset of T cells is involved in the early immune response by differentiating from naive T0 cells?
How do effector T cells reach the site of infection?
How do effector T cells reach the site of infection?
What type of cells do TH2 cells primarily assist in activating?
What type of cells do TH2 cells primarily assist in activating?
Which statement best describes TH17 cells?
Which statement best describes TH17 cells?
What interaction is crucial for the activation of T cells via CD40L?
What interaction is crucial for the activation of T cells via CD40L?
Study Notes
Thymus Functionality
- Positive Selection: Promotes survival of T cells with TCRs that recognize self peptides with weak affinity, enabling recognition of foreign antigens.
- T Cell Differentiation: Immature T cells expressing both CD4 and CD8 differentiate into CD4+ T cells or CD8+ T cells.
- Negative Selection: Eliminates immature T cell clones with strong affinity for self antigens in the thymus through apoptosis, maintaining self-tolerance and preventing autoimmunity.
- Naïve T Cell Migration: Mature, immunocompetent T cells enter circulation and peripheral lymphoid tissues.
Structure of T Cell Antigen Receptor (TCR)
- TCR Composition: Composed of two peptide chains, α and β.
- Binding Sites: The α1 and β1 domains (V domains) form the antigen binding site, while α2 and β2 (C domains) are constant regions.
- CD3 Complex: The α/β dimer associates with CD3, which is essential for TCR expression and signaling activation.
Structure of B Cell Antigen Receptor (BCR)
- BCR Configuration: Consists of a single IgM molecule on the B cell surface, often with IgD in mature B cells.
- Heterodimers: Ig-α/Ig-β heterodimers associate with the membrane Ig subunits.
- Light and Heavy Chains: Comprised of two heavy chains and two light chains; light chains include kappa (κ) and lambda (λ) types, while heavy chains contain one variable and three constant domains.
Steps of B Cell Maturation in Bone Marrow
- Pro-B Cells: Initial recombination of Ig genes at the heavy chain locus.
- Pre-B Cells: Express heavy chains mu (μ) of IgM for pre-BCR formation.
- Immature B Cells: Express a complete IgM molecule, consisting of two heavy and two light chains (κ).
- Positive Selection: Functional membrane Ig molecules receive survival signals.
- Negative Selection: High avidity self-receptor expressing B cells undergo clonal deletion.
- Mature B Cells: Leave bone marrow, express IgM and IgD, secrete antibodies as plasma cells upon activation.
Subsets of Mature B Cells
- Follicular B Cells: Majority of mature B cells, express IgD, migrate between lymphoid organs.
- Marginal Zone B Cells: Located in the spleen, respond rapidly to blood-borne microbes, differentiate into short-lived plasma cells.
Cell Mediated Immunity (CMI)
- Professional APCs: Include macrophages, dendritic cells, and B lymphocytes that process antigens and present peptide fragments via MHC molecules.
MHC Molecules
- MHC Classification: Divided into Class I (all nucleated cells) and Class II (immune cells only).
- Class I Structure: Comprises a heavy chain complexed with β2 microglobulin, presenting peptides to CD8+ TC cells.
- Class II Structure: Forms from two polypeptide chains with a peptide-binding site for CD4+ TH cells.
Antigen Processing and Presentation
- Endocytic Pathway (Class II): Exogenous antigens are internalized, degraded, and presented to CD4+ T helper cells.
- Cytosolic Pathway (Class I): Endogenous proteins are degraded and presented to CD8+ cytotoxic T cells.
T Cell Activation
- T Cell Subsets: Include CD4+ T helper cells (TH1, TH2, TH17, Tregs) and CD8+ T cytotoxic cells.
- Activation Signals:
- First Signal: Antigen recognition via MHC-TCR interaction.
- Second Signal: Costimulatory signals through CD28-B7 interaction and CD40-CD40L engagement.
Migration of Effector T Cells
- Adhesion Molecules: Allow effector T cells to migrate to infection sites via blood vessels, following chemokine signals.
Functions of TH1 Cells
- Differentiation Inducers: IL-12 and INF-gamma promote differentiation of naive TH0 into TH1 cells during an early immune response.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
This quiz explores the key concepts related to B cell receptors, their maturation, and the selection processes they undergo. It covers the composition of antigen binding sites, the role of pre-BCR, and the characteristics of different types of B cells. Test your understanding of immunology related to B cell function and development.
