Immunology: BCR and Antibody Structure Quiz

Session Introduction & Logistics

• The session is on Immunology (BSS020N232Y)
• The session begins at 9 a.m.
• The session will be recorded and made available online later.
• Check internet/sound/video before 9 a.m. if there are issues.
• Troubleshooting steps are provided for internet connectivity problems.

Troubleshooting Internet Connectivity

• Use a fully updated Chrome browser.
• Check internet connectivity under "My Settings."
• Get closer to your Wi-Fi.
• Close other applications on the computer.
• Contact Moodle or IT Helpdesk for further assistance.

Session Crashing

• The session may crash but will be restored within 15 minutes.
• If restoration is unsuccessful, it's acceptable to leave the session.
• Participants will be emailed a recording and a replacement lecture, if necessary.

Lecture Content: Adaptive Immunity: B Cells (Page 2)

• The lecture is on adaptive immunity, specifically focusing on B cells.
• Lecturer is Robert Busch, PhD.
• Email address and office location are provided.
• Usual contact hours are given: Monday-Wednesday 1-2 pm, Friday 2-3 pm.
• The session includes access to online recordings and live recordings.
• Booking an in-person session is available on Fridays

Reading (Page 3)

• Review previous lectures on immunology and T cells.
• Review lectures on cell signaling from Cell Biology.
• Study material is available on the Immunology Moodle site.
• Required material includes chapters on adaptive immunity, antibodies, and B lymphocytes from a good immunology textbook.
• One suggested book is Janeway's Immunobiology, 7th edition (Garland Science, 2008) or a digital version available online.

Review: Innate vs. Adaptive Immunity (Page 4)

• The lecture provides a review comparing innate and adaptive immunity mechanisms in terms of pathogen recognition.
• The method for pathogen recognition by the different mechanisms is the focus.

Specific Recognition of Pathogens (Page 5)

• The lecture describes the role of lymphocytes in antigen receptors' specific pathogen recognition.

Content of Subsequent Lectures (Page 6)

• Review of Antibody structures and specific antigen interactions.
• The genetic basis of antigen specificity and various antibody classes and functions.
• B-cell activation, fate during immune responses.
• B-cell development, tolerance, regulatory B cells.
• Monoclonal antibodies' use in disease diagnosis and treatment.

Antibody/Antigen Interactions (Page 7)

• The lecture is on the structural biology of antibody-antigen (Ab/Ag) interactions.

Antibody Architecture (Page 8)

• The structures of antibodies, emphasizing different polypeptide chains, disulfide bonds within the domains
• The process of proteolytic fragmentation and its results are discussed.

Antibody-Antigen Complexes (Page 9)

• This section covers the crystal structure of antibody–antigen complexes, specifically focusing on anti-lysozyme complexes.

Immunoglobulin Superfamily (Page 10)

• The tertiary structure of immunoglobulins and the details of immunoglobulin superfamily (IgSF) domains are discussed. Includes the general structure, binding of antigens, and loop interactions with antigens.

Antigen Recognition (Page 11)

• The lecture addresses the recognition of the model antigen (hen egg lysozyme) by different antibodies.
• The interactions between the antibodies and the exposed patches or epitopes on the antigen.

IgSF in Other Cell Surface Receptors (Page 12)

• The recurring immunoglobulin superfamily (IgSF) fold describes the architecture in various cell surface receptors, including CD antigens.
• The role of CD antigens in interactions with other components is discussed.

Antibody Structural Biology Summary (Page 13)

• Summarize the structural biology of antigen recognition by antibodies.
• B and T lymphocytes are shown to have cell surface receptors for antigen binding.
• Antibody (BCR) and T cell receptors (TCR) share Ig superfamily structural features, with differences in specific arrangements.
• Antibodies have Y-shaped, membrane-bound, soluble forms made of two chains each.
• BCR primarily interacts with intact antigens (e.g., proteins, carbohydrates) in their natural form.
• Compare and contrast BCR and TCR from previous lectures.

Antibody Specificity (Page 14)

• Discuss genetic basis and antigen specificity of antibodies.

Clonal Selection and Memory (Page 15)

• Clonal selection as a mechanism to create diversity in antigen-stimulated immune response
• Distinction between primary and secondary immune responses.

Antibody Diversity (Page 16)

• Describe how antibody diversity is encoded in terms of the repertoire of immunoglobulin genes.
• Sequencing estimates in individual B lymphocytes are used to determine the bounds of possible antibody repertoires.
• The diversity of the Light chains and Heavy chains is discussed.

Creation of Antibody Diversity (Page 17)

• Distinguish between additive and combinatorial diversity in antibody creation.

Inherited Germline Antigen Receptor Genes (Page 18)

• Describe the inherited germline antigen receptor genes and their role in generating the variable regions of immune receptors.

Somatic Gene Rearrangement (Page 19)

• Understand how somatic gene rearrangement is involved in antibody diversity.
• Describe a process for creating diversity in antibody production.

Combinatorial Diversity (Page 20)

• Discuss the combinatorial process of creating antibody diversity.
• Details of the number of functional gene segments, including V (variable), D (diversity), and J (joining) segments, are presented.

B-cell and T-cell Genes (Page 21)

• Describes the function of RAG 1 and RAG 2 genes expressed during early lymphocyte development
• Describes the role of proteins in recognising specific short repeated DNA sequences, which are located on either side of the V, D, and J segments.
• Recombinase enzymes and their use to repair DNA are highlighted.
• DNA is excised, constructing ring structures.

Imprecise Joining (Page 22)

• Details the mechanisms of imprecise joining at V(D)J junctions and the generation of antibody diversity.
• Discuss the roles of palindromic and non-templated sequences.

Transcription, Splicing, and Translation (Page 23)

• This section covers the transcription, splicing, and translation of rearranged Ig genes to form antibodies.
• The section describes the process of generating antibodies from antibody genes by transcription and subsequent processes.
• The significance of the junctions V(D)J is highlighted.

BCR Diversity (Page 24)

• The summary of mechanisms used by B cells to create antibody diversity.
• Focuses on antibody variability, including VDJ recombination effects within the L chains, H chains, and combinations of both.
• Describes theoretical antibody production amounts—approximately 1012 to 1018 distinct BCR gene sequences. These amounts are sufficient to account for BCR clonal diversity.
• The impact of these mechanisms on TCR genes during T cell development is highlighted.

Antibody Classes' Effector Functions (Page 25)

• Focuses on the activities and roles of antibodies that help combat infections.

Soluble Antibody Fc Portions' Effects (Page 26)

• Discuss the Fc portion of soluble antibodies in determining their defensive functions.
• Describe the distinctions between different antibody classes/types based on their constant regions.

IgM Antibody Features (Page 27)

• Description of IgM, including its characteristics—first antibody secreted in primary responses.
• Describe IgM's characteristics: production does not require T-cell assistance, pentameric structure, low affinity, but high valency.
• Discuss IgM's roles in activating the classical complement pathway and its absence of binding to Fc receptors of phagocytes and mast cells.

IgD Antibody Features (Page 28)

• IgD is a membrane-bound antibody that does not get secreted.
• IgM-producing naive B cells often also produce IgD.

IgG Antibody-Producing Responses (Page 29)

• Describe secondary immune response generation of other antibody classes, focusing on IgG.
• A graph shows that IgG is produced primarily in secondary immune responses.

IgG Features (Page 30)

• Characteristics of IgG are discussed, with emphasis on its role in primary and secondary responses.
• The roles of Th cells, class switching, and affinity maturation in IgG production are examined.

IgA Antibody Function (Page 31)

• Feature analysis of IgA, highlighting the class of antibody's production in secondary responses; roles in mucosal immunity.

IgE Antibody Features (Page 32)

• IgE's critical role in immediate hypersensitivity (allergic reactions) and its characteristics—secreted as a monomer in secondary responses.
• Describes its binding to FcRe, crosslinking, degranulation, and worm defenses.

Break (Page 33)

• The session will break.

IgM/IgG Complementary Activation (Page 34)

• IgM and IgG antibodies binding to bacterial antigens to improve complement activation by binding to complementary bacterial surface antigens and initiating a complement response.

Receptors for Ig Fc domains (Page 35)

• Explains the receptors for Fc domains of Ig.

Antibody-Coated Bacteria (Page 36)

• Illustrates how phagocytes use Fc receptors and complement receptors to internalize bacteria coated with antibodies.

Killing of antibody-coated cells (Page 37)

• Describes the process where natural killer (NK) cells kill IgG-coated target cells, like virus-infected cells, using antibody-dependent cellular cytotoxicity (ADCC).

Mast Cell Histamine Reaction (Page 38)

• The lecture shows the mechanism of how the crosslinking of allergen-specific IgE to receptors on mast cells triggers an allergic reaction.
• The roles of Fc receptors on mast cells, allergens, and IgE antibodies in histamine release.

Antibody Class Summary (Page 39)

• Summary of the key characteristics of different antibody classes.
• Includes information about molecular weight(kDa), serum levels, and half-life.

Antibody Class Genetic Basis (Page 40)

• Genetic basis of the classification of the antibody class (isotypes).

Antibody Constant Region Production (Page 41)

• Explain how antibodies with different constant regions are generated.
• Importance of coexpressed antibody types and class-switch recombination to various antibody types.

IgM/IgD Co-expression (Page 42).

• Alternative splicing is used in the production of IgM and IgD.

Class Switch Recombination (Page 43)

• Describes a mechanism for class switch recombination.
• Role of cytokines from helper T cells in inducing class switch recombination, which is a distinct process from V(D)J recombination; thus, independent of antigenicity.
• Explanation of how class switch recombination is induced by helper T cell cytokines.

B Cell Activation (Page 44)

• Introduction to B-cell activation and fate.

B-cell Activation Summary (Page 45)

• Explanation of B-cell activation, focusing on different steps involved (naive B cell, GC B cell, plasmablast, long-lived plasma cell, and memory B cell).
• Role of T helper cells in B-cell activation.

BCR & Coreceptor Signaling (Page 46)

• The signaling pathways involved in activating B cells.
• BCR and coreceptor activation by antigen binding.
• B-cell proliferation and differentiation into memory cells and antibody-secreting cells.

Major B Cell Subsets (Page 47)

• Classification and characteristics of B cell subtypes.
• Focuses on the major subsets of B cells found in lymphoid, mucosal tissues, and peritoneal cavity.

T-cell Help for B-cells (Page 48)

• The detailed process of B-cell activation and the importance of T cell help.
• The roles of follicular B and helper T cells' interaction and the use of chemokines to promote interaction and activation are discussed.

Somatic Hypermutation (Page 49)

• Explain how somatic hypermutation works.
• Describe the processes in B cell expansion, negative selection, and positive selection involved in creating antibodies with increased affinity for the antigen.

Germinal Center Function (Page 50)

• Description of the germinal center's involvement in T-cell help, class switching, and affinity maturation.
• Explain how T cells, dendritic cells, and other cell types interact in the germinal center.

Plasma Cell Differentiation (Page 51)

• Details of how activated B cells develop into antibody-secreting plasma cells.
• Describes the markers used to distinguish activated B-cells from mature B-cells.

RNA Splicing and Soluble Antibody Production (Page 52)

• Explain how RNA splicing differs to create and release soluble antibodies.

B-cell Development and Tolerance (Page 53)

• Processes by which B cells develop and achieve self-tolerance.

B-cell lineages and progenitor development (Page 54)

• The stages through which B lineage cells develop and how they acquire tolerance to self-antigens.

B-1 Cell Development (Page 55)

• Description of B-1 cells' different lineage, separate development from other B cells, and their position and function in the immune system.
• Mentioning B1 cells in the peritoneal cavity and intestine

Regulatory B Cells (Page 56)

• Describes properties of regulatory B cells, their roles in preventing immunopathology and promoting tolerance to self-antigens and other immune responses.

Clinical Applications of B-cell Immunology (Page 57)

• Overview of the use of antibodies in vaccinations, diagnostic testing, and treatment.

Immunization (Page 58)

• Explain how vaccination strategies, using various preparations of antigens and antibody types, can protect against viral and bacterial infections.
• Details on active and passive immunization.

Monoclonal Antibodies (Page 59)

• The methods and mechanisms (using DNA technology or hybridoma) for creating monoclonal antibodies.

Antibody Tests (Page 60)

• The enzyme-linked immunosorbent assay (ELISA) method is used to detect specific antibodies.
• Different types of tests to look for antibodies, including sandwich and indirect ELISAs.

Monoclonal Antibody Tissue Investigations (Page 61)

• Description of monoclonal antibodies' use in diagnostics, specifically focusing on immunohistochemistry, for identifying specific antigens in tissues.
• Illustrate how microscopic staining processes identify the antigens that make up the tissue.

Neutralizing Antibody Tests (Page 62)

• Discuss how these tests predict the efficiency of antibodies in combating viral infections.
• Describe a method for detecting neutralizing antibodies, using haemagglutination assay.

Monoclonal Antibodies for Therapy (Page 63)

• Explain how monoclonal antibody therapy is used in malignancies and autoimmune conditions.
• Discuss the various roles and targets of monoclonal antibodies.

Reducing Antibody Inter-Species Differences (Page 64)

• Focus on strategies to decrease differences between mouse and human antibody production.
• Explanation of various approaches to reduce antibody differences between species.

Anti-TNF Therapies (Page 65)

• Explain how monoclonal antibodies, such as anti-TNFs, can be used in rheumatoid arthritis treatment.

Anti-TNF Therapies (Page 66)

• Explain how different anti-TNF therapies work.
• Explanation of the drugs used for anti-TNF therapies.

Antibodies, B-cells, and Summary (Page 67)

• Overview of antibodies and B cells.
• Summary of the key features, interactions, and functions of antibodies and B cells, including somatic hypermutation, class switching, and B cell subsets.

Thank You (Page 68)

• Session conclusion and closing remarks.

Test your knowledge on the structure and function of antibodies and B cell receptors (BCRs). This quiz covers topics such as hypervariable loops, epitopes, molecular weight of immunoglobulin domains, and genetic rearrangement in lymphocytes. Enhance your understanding of immunological principles and the diversity of immune responses.