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18.4 B Lymphocytes and Humoral Immunity

4 min readLast Updated on June 18, 2024

B cells are crucial players in our immune system, developing from stem cells in bone marrow. They undergo a complex maturation process, creating unique receptors to recognize specific antigens. This diversity allows our bodies to defend against a wide range of pathogens.

B cell activation can be T-dependent or T-independent, leading to antibody production. Primary and secondary antibody responses differ in speed and effectiveness. Clonal selection, affinity maturation, and class switching fine-tune our immune defenses, making them more potent over time.

B Lymphocyte Development and Activation

Development of B cells

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  • B cells originate from hematopoietic stem cells in the bone marrow
  • Pro-B cells undergo V(D)J recombination to generate unique B-cell receptors (BCRs)
    • Recombination of variable (V), diversity (D), and joining (J) gene segments creates vast diversity in antigen recognition
    • Successful recombination leads to the formation of pre-B cells expressing a functional pre-BCR
  • Pre-B cells express surface IgM and differentiate into immature B cells
  • Immature B cells undergo negative selection to eliminate self-reactive cells
    • Cells that bind strongly to self-antigens are eliminated through apoptosis or undergo receptor editing to change their specificity
  • Surviving immature B cells migrate to secondary lymphoid organs (spleen, lymph nodes) where they mature into naïve B cells
    • Further maturation into mature, naïve B cells expressing both surface IgM and IgD as antigen receptors

B-cell vs T-cell receptors

  • B-cell receptors (BCRs) are membrane-bound immunoglobulins (antibodies)
    • Composed of two heavy chains and two light chains forming a Y-shaped structure
    • Antigen-binding site formed by the variable regions of heavy and light chains determines specificity
    • Recognize and bind to specific epitopes on soluble antigens in their native conformation
  • T-cell receptors (TCRs) are heterodimeric protein complexes
  • BCRs can directly bind to native antigens, while TCRs require processed peptide antigens presented by MHC for recognition

B Cell Activation and Antibody Response

T-dependent vs T-independent activation

Primary vs secondary antibody responses

  • Primary antibody response occurs upon first exposure to an antigen
    • Characterized by a lag phase (7-10 days) before antibody production begins as naïve B cells become activated
    • Predominantly produces IgM antibodies with lower affinity binding to the antigen
    • Generates memory B cells specific to the antigen for future encounters
  • Secondary antibody response occurs upon subsequent exposure to the same antigen
    • Characterized by a shorter lag phase (1-3 days) and a more rapid and robust antibody production due to memory B cells
    • Predominantly produces high-affinity IgG antibodies, with some IgA and IgE for enhanced antigen clearance
    • Memory B cells quickly differentiate into plasma cells, leading to a faster and stronger response compared to the primary response
  • Secondary response exhibits higher antibody titers, improved antibody affinity, and a more rapid clearance of the antigen

Clonal Selection and Affinity Maturation

  • Clonal selection theory explains how B cells specific to an antigen are selected for expansion
    • Only B cells with receptors that bind to the antigen are activated and proliferate
    • This process results in the production of antibody-secreting plasma cells and memory B cells
  • Affinity maturation improves antibody affinity over time
    • Somatic hypermutation introduces mutations in the variable regions of antibody genes
    • B cells with higher affinity antibodies are preferentially selected for survival and expansion
  • Class switching allows B cells to produce different antibody isotypes (IgG, IgA, IgE) while maintaining antigen specificity
    • This process enhances the versatility of the antibody response

Complement System and Effector Functions

  • The complement system enhances antibody-mediated immunity (antibody-mediated immunity)
    • Antibodies can activate the classical complement pathway
    • Complement proteins aid in pathogen elimination through various mechanisms
  • Opsonization is a process where antibodies coat pathogens, making them more easily recognized and engulfed by phagocytes

Key Terms to Review (102)

Affinity maturation: Affinity maturation is the process by which B cells produce antibodies with increased binding affinity for their specific antigen during an immune response. It occurs primarily in the germinal centers of lymph nodes.
Affinity Maturation: Affinity maturation is a process that occurs during the adaptive immune response, where B cells undergo somatic hypermutation and clonal selection to produce antibodies with increased binding affinity for their target antigen. This process helps to refine and optimize the humoral immune response over time.
Anergy: Anergy is a state in which immune cells, particularly T and B lymphocytes, become non-responsive to their specific antigen. This prevents an immune response even when the antigen is present.
Antibody-Mediated Immunity: Antibody-mediated immunity, also known as humoral immunity, is the branch of the adaptive immune system that involves the production of antibodies by B lymphocytes to neutralize or eliminate extracellular pathogens and toxins. It is a crucial defense mechanism against a wide range of infectious agents.
Antigen-binding sites: Antigen-binding sites are specific regions on an antibody molecule that interact directly with antigens. These sites determine the antibody's specificity for a particular antigen.
Antigen-Presenting Cells (APCs): Antigen-presenting cells (APCs) are a diverse group of immune cells that play a crucial role in initiating and regulating the adaptive immune response. These specialized cells are responsible for capturing, processing, and presenting antigenic peptides to T lymphocytes, triggering their activation and subsequent immune reactions.
Apoptosis: Apoptosis is a form of programmed cell death that occurs in multicellular organisms. It plays a crucial role in regulating immune responses and maintaining cellular homeostasis.
Apoptosis: Apoptosis is a highly regulated form of programmed cell death that occurs in multicellular organisms. It is a crucial process involved in various aspects of the immune system, viral life cycles, and cellular defenses against disease.
Autoimmunity: Autoimmunity is a condition where the immune system mistakenly attacks the body's own cells, tissues, and organs. It involves an inappropriate response by adaptive immunity, particularly B lymphocytes and T lymphocytes.
B lymphocytes: B lymphocytes, also known as B cells, are a type of white blood cell crucial for the adaptive immune response. They produce antibodies to neutralize pathogens and remember past infections for faster responses in the future.
B Lymphocytes: B lymphocytes, also known as B cells, are a type of white blood cell that play a crucial role in the adaptive immune response. They are responsible for the production of antibodies, which help neutralize and eliminate foreign pathogens and toxins from the body.
B-cell receptors (BCRs): B-cell receptors (BCRs) are antigen-binding molecules expressed on the surface of B lymphocytes. They play a crucial role in the recognition and binding of specific antigens, initiating the humoral immune response.
BCR: B Cell Receptor (BCR) is a membrane-bound immunoglobulin molecule present on the surface of B lymphocytes. It plays a crucial role in recognizing specific antigens and initiating an immune response.
Bone marrow: Bone marrow is a spongy tissue found inside certain bones, such as the hip and thigh bones. It is crucial for the production of blood cells, including those vital for the immune system.
CD4: CD4 is a glycoprotein found on the surface of immune cells such as T helper cells, monocytes, macrophages, and dendritic cells. It plays a crucial role in the immune system by aiding in the activation of T cells through interaction with MHC class II molecules.
CD40L: CD40L, also known as CD154 or TNFSF5, is a transmembrane protein that belongs to the tumor necrosis factor (TNF) superfamily. It is primarily expressed on the surface of activated T cells and plays a crucial role in the activation and regulation of B lymphocytes, as well as in the humoral immune response.
Class switching: Class switching is a biological mechanism in which a B cell changes the class of antibody it produces without altering the specificity for antigen. This process involves recombination at the DNA level to switch from one immunoglobulin (Ig) class to another, such as from IgM to IgG.
Class Switching: Class switching, also known as isotype switching, is a biological process that occurs in B lymphocytes during an adaptive immune response. It involves the rearrangement of the constant region of the immunoglobulin heavy chain gene, allowing the B cell to produce different classes or isotypes of antibodies while maintaining the same antigen-binding specificity.
Clonal proliferation: Clonal proliferation is the process by which specific lymphocytes rapidly multiply after recognizing a particular antigen. This ensures that there are enough immune cells to effectively respond to and eliminate the pathogen.
Clonal Selection: Clonal selection is a fundamental principle in immunology that describes how the adaptive immune system generates a diverse repertoire of antigen-specific lymphocytes and selectively expands those that recognize and bind to foreign pathogens. It is a crucial mechanism that underpins the specific adaptive immune response.
Common lymphoid progenitor cells: Common lymphoid progenitor cells are a type of hematopoietic stem cell that gives rise to all the cells of the lymphoid lineage, including B cells, T cells, and natural killer cells. These progenitor cells are a crucial link between the innate and adaptive immune responses.
Complement system: The complement system is a group of proteins that enhance the ability of antibodies and phagocytic cells to clear pathogens from an organism. It forms part of the innate immune response and also helps bridge innate and adaptive immunity.
Complement System: The complement system is a complex network of proteins that work together as part of the immune system's chemical defenses. It is a crucial component of the body's innate and adaptive immune responses, playing a vital role in inflammation, pathogen elimination, and the clearance of immune complexes.
Constant region: The constant region is the part of an antibody's structure that remains the same among different antibodies of the same class. It is responsible for mediating interactions with immune cells and effector functions.
Cross-linkage: Cross-linkage refers to the binding of multiple antigens by a single antibody, resulting in the formation of a complex. This process is crucial for the activation and effectiveness of the immune response.
DNA ligase: DNA ligase is an enzyme that facilitates the joining of DNA strands by catalyzing the formation of a phosphodiester bond. It is essential in DNA replication and repair processes.
Epitopes: Epitopes are specific regions on an antigen that are recognized and bound by antibodies or T-cell receptors. They play a crucial role in the specificity of the immune response.
Epitopes: Epitopes, also known as antigenic determinants, are the specific regions on the surface of an antigen that are recognized and bound by antibodies or T cell receptors. These unique molecular structures on the surface of pathogens or foreign substances are crucial for the activation of the adaptive immune response.
Free protein antigens: Free protein antigens are foreign proteins that can trigger an immune response without being attached to a cell or pathogen. They are recognized by B cells, leading to the production of antibodies.
Genetic rearrangement: Genetic rearrangement involves the reorganization of genetic material, particularly in lymphocytes, to produce diverse antigen receptors. It plays a crucial role in the adaptive immune response by generating unique T and B cell receptors.
Germinal Centers: Germinal centers are specialized microanatomical structures that form within secondary lymphoid organs, such as lymph nodes and the spleen, during the adaptive immune response. They serve as sites for the proliferation, differentiation, and selection of B lymphocytes that have encountered and bound to their cognate antigen.
Heavy chains: Heavy chains are the larger polypeptide subunits of an antibody molecule, essential for determining its class and function. They form the backbone of the antibody structure and contribute to antigen binding.
Heavy Chains: Heavy chains are one of the two main types of polypeptide chains that make up antibody molecules. They are larger in size and more complex in structure compared to the light chains, and play a crucial role in the function and diversity of antibodies.
Helper T cells: Helper T cells are a type of T lymphocyte that play a central role in the adaptive immune response by activating other immune cells. They are essential for initiating and regulating both cellular and humoral immunity.
Helper T Cells: Helper T cells are a subtype of T lymphocytes that play a crucial role in coordinating and regulating the adaptive immune response. They act as the orchestrators of the immune system, providing essential signals and support to other immune cells to mount an effective defense against pathogens and foreign invaders.
Hematopoietic stem cells: Hematopoietic stem cells are multipotent stem cells capable of differentiating into all types of blood cells, including T and B lymphocytes. They play a crucial role in the immune system by generating the cellular components necessary for adaptive immunity.
Hematopoietic Stem Cells: Hematopoietic stem cells are a type of multipotent stem cell found in the bone marrow that have the ability to self-renew and differentiate into all the various blood cell types, including red blood cells, white blood cells, and platelets. They are the precursors to the cellular components of the immune system and play a crucial role in maintaining homeostasis and defending the body against pathogens.
Humoral immunity: Humoral immunity is a component of the adaptive immune system that involves the production of antibodies by B cells. These antibodies circulate in the blood and lymphatic system to neutralize pathogens.
Humoral Immunity: Humoral immunity refers to the antibody-mediated immune response, which involves the production of antibodies by B lymphocytes to neutralize and eliminate extracellular pathogens and toxins. It is a crucial component of the adaptive immune system that provides long-lasting protection against specific antigens encountered by the body.
Hyperpigmentation: Hyperpigmentation is the darkening of an area of skin caused by increased melanin production. It can be triggered by various factors, including autoimmune disorders.
IgA: IgA, or immunoglobulin A, is a type of antibody that plays a crucial role in the body's adaptive immune response. It is the predominant antibody found in mucosal areas, such as the respiratory, digestive, and urogenital tracts, where it helps protect these surfaces from invading pathogens.
IgD: IgD is an immunoglobulin isotype that is primarily expressed on the surface of mature, naïve B cells. It serves as an antigen receptor, playing a crucial role in the activation and differentiation of B cells as part of the adaptive immune response.
IgE: IgE is a class of antibody that plays a crucial role in the body's immune response, particularly in the context of allergic reactions and hypersensitivity. This antibody is primarily responsible for the immediate, or type I, hypersensitivity reactions that occur when the body is exposed to specific allergens.
IgG: IgG, or Immunoglobulin G, is the most abundant type of antibody found in the human body. It plays a crucial role in the adaptive immune response, contributing to pathogen recognition, phagocytosis, and the regulation of humoral immunity.
IgM: IgM is the largest antibody isotype found in the human body. It is the first antibody produced during an initial immune response and plays a crucial role in the early stages of the adaptive immune system's defense against pathogens.
Immature B cells: Immature B cells are a developmental stage of B lymphocytes that have not yet fully matured. These cells are produced in the bone marrow and play a crucial role in the humoral immune response.
Immunoglobulins: Immunoglobulins are specialized glycoproteins produced by B cells that function as antibodies in the immune response. They play a critical role in identifying and neutralizing pathogens such as bacteria and viruses.
Immunoglobulins: Immunoglobulins, also known as antibodies, are glycoprotein molecules produced by plasma B cells that recognize and bind to specific antigens, initiating an immune response. They play a crucial role in the humoral immune system and are involved in various immunological processes described in the topics of 18.2 Major Histocompatibility Complexes and Antigen-Presenting Cells, 18.4 B Lymphocytes and Humoral Immunity, 19.4 Immunodeficiency, and 20.5 Fluorescent Antibody Techniques.
Internalization: Internalization is the process where a cell engulfs and incorporates foreign particles, such as antigens or pathogens, into its cytoplasm. This is a critical step in the immune response for antigen processing and presentation.
Isotype switching: Isotype switching is a biological mechanism in B cells that changes the class of antibody they produce without altering the antigen specificity. This process allows for a more effective immune response by producing different types of antibodies (IgG, IgA, etc.) tailored to specific pathogens.
Lag period: The lag period is the initial phase after exposure to an antigen during which no antibodies are detectable in the blood. This period allows for the activation and proliferation of specific B lymphocytes.
Latent period: The latent period is the time interval between exposure to a pathogen and the appearance of detectable antibodies in the bloodstream. It is a crucial phase in the development of humoral immunity.
Light chains: Light chains are the smaller polypeptide subunits of antibodies, forming part of the antibody's antigen-binding site. They pair with heavy chains to create functional immunoglobulin molecules.
Light Chains: Light chains are one of the two types of polypeptide chains that make up an antibody molecule. They are smaller in size compared to the heavy chains and contribute to the antigen-binding capabilities of the antibody.
Linked recognition: Linked recognition is a process whereby B cells and T helper cells recognize different epitopes of the same antigen to initiate a stronger immune response. This collaboration is essential for the production of high-affinity antibodies.
Lipopolysaccharide: Lipopolysaccharide (LPS) is a complex molecule found in the outer membrane of Gram-negative bacteria. It is a key component of the bacterial cell wall and plays a crucial role in various aspects of microbiology, immunology, and pathogenesis.
Memory B cells: Memory B cells are a type of B lymphocyte that retains information about pathogens after an initial immune response, allowing for a faster and more efficient response upon re-exposure to the same pathogen. They play a crucial role in long-term immunity.
Memory B Cells: Memory B cells are a type of B lymphocyte that retain information about past encounters with specific antigens, allowing for a rapid and robust antibody response upon re-exposure to the same antigen. They are a crucial component of the adaptive immune system's humoral response.
MHC I: MHC I (Major Histocompatibility Complex Class I) molecules are cell surface proteins essential for the immune system to recognize infected or abnormal cells. They present endogenous antigens to cytotoxic T lymphocytes, initiating an immune response.
MHC II: MHC II (Major Histocompatibility Complex class II) are proteins found on the surface of certain immune cells that present antigens to T-helper cells. They play a crucial role in initiating the immune response by displaying foreign peptides to T cells.
MHC Molecules: MHC (Major Histocompatibility Complex) molecules are a group of cell surface proteins that play a crucial role in the immune system's ability to recognize and respond to foreign or abnormal substances within the body. These molecules are essential for the presentation of antigenic peptides to T cells, triggering an immune response.
Naïve B cells: Naïve B cells are immature B lymphocytes that have not yet encountered their specific antigen. They are the precursors to activated B cells, which play a crucial role in the humoral immune response by producing antibodies against invading pathogens.
Naïve mature B cells: Naïve mature B cells are immune cells that have completed development in the bone marrow but have not yet encountered their specific antigen. They circulate in the peripheral lymphoid organs, ready to initiate an immune response upon antigen exposure.
Negative selection: Negative selection is the process by which T lymphocytes (T cells) that react strongly with self-antigens are eliminated in the thymus to prevent autoimmune responses. This ensures that only T cells tolerant to self-antigens mature and enter the peripheral immune system.
Negative Selection: Negative selection is a crucial process in the development and maturation of B lymphocytes, which play a central role in the humoral immune response. It serves as a quality control mechanism to eliminate self-reactive B cells, preventing autoimmunity.
Opsonization: Opsonization is the process by which pathogens are marked for ingestion and destruction by phagocytes. This marking involves the coating of antigens with opsonins, such as antibodies or complement proteins.
Opsonization: Opsonization is the process by which certain molecules, known as opsonins, bind to the surface of a pathogen or foreign particle, making it more susceptible to phagocytosis by immune cells such as macrophages and neutrophils. This process enhances the recognition and engulfment of the target by phagocytes, improving the efficiency of the immune response.
PAMPs: Pathogen-associated molecular patterns (PAMPs) are molecular structures found on pathogens that are recognized by the innate immune system. These patterns trigger an immune response aimed at eliminating the pathogen.
Pattern Recognition Receptors: Pattern recognition receptors (PRRs) are specialized proteins expressed on the surface of immune cells that can detect and bind to specific molecular patterns associated with pathogens or damaged cells. These receptors play a crucial role in the body's innate immune response by triggering signaling cascades that activate various defense mechanisms.
Pattern recognition receptors (PRRs): Pattern recognition receptors (PRRs) are proteins on or in cells that identify pathogen-associated molecular patterns (PAMPs) to initiate an immune response. They play a crucial role in the body's innate immune system by recognizing and responding to microbial invaders.
Pentameric IgM: Pentameric IgM is an immunoglobulin composed of five IgM monomers linked together, forming a large, complex structure. It plays a crucial role in the initial stages of the immune response by effectively binding to antigens and activating complement pathways.
Plasma cells: Plasma cells are differentiated B lymphocytes that produce and secrete large quantities of antibodies. They play a critical role in the humoral immune response by targeting specific antigens.
Plasma Cells: Plasma cells are terminally differentiated B lymphocytes that are responsible for the production and secretion of antibodies, playing a crucial role in the humoral immune response. These specialized cells arise from activated B cells and are central to the adaptive immune system's ability to provide long-lasting protection against pathogens.
Polysaccharides: Polysaccharides are large, complex carbohydrate molecules composed of long chains of monosaccharide units. They serve various structural and functional roles in living organisms, including energy storage and structural support.
Positive selection: Positive selection is the process by which developing B lymphocytes (B cells) in the bone marrow are selected for their ability to bind to self-MHC molecules, ensuring they can participate in immune responses. This step ensures that B cells can function properly within the immune system.
Pre-B Cells: Pre-B cells are an early stage of B lymphocyte development, representing a transitional phase between pro-B cells and immature B cells. These cells play a crucial role in the humoral immune response by giving rise to mature, functional B cells capable of producing antibodies.
Pre-BCR: The pre-B cell receptor (pre-BCR) is a crucial checkpoint in the development of B lymphocytes, acting as a signaling complex that guides the maturation of B cells from the pro-B cell to the pre-B cell stage. It plays a pivotal role in the process of B cell differentiation and the eventual production of functional, antigen-specific B cell receptors (BCRs).
Primary antibody response: The primary antibody response is the initial immune response to an antigen, characterized by the production of IgM antibodies followed by IgG antibodies. It typically takes 7-14 days to reach its peak after the first exposure to an antigen.
Primary Antibody Response: The primary antibody response is the initial immune reaction that occurs when the body is first exposed to a specific antigen. It involves the activation and proliferation of naive B lymphocytes, leading to the production of antibodies against the encountered antigen.
Pro-B Cells: Pro-B cells are the earliest stage of B lymphocyte development, originating from hematopoietic stem cells in the bone marrow. These immature B cells undergo a series of genetic rearrangements and maturation processes to eventually become functional, antigen-responsive B cells capable of participating in the humoral immune response.
Receptor Editing: Receptor editing is a process in which B lymphocytes modify their antigen receptor genes to produce a different antibody, allowing them to avoid autoreactivity and the development of autoimmune disorders. This process is crucial for maintaining self-tolerance and preventing the immune system from attacking the body's own tissues.
Repetitive epitope units: Repetitive epitope units are multiple identical antigenic determinants present on a single antigen molecule. These repeated structures can enhance the immune system's ability to recognize and respond to the pathogen.
Secondary Antibody Response: The secondary antibody response is the enhanced immune reaction that occurs upon re-exposure to a specific antigen. It involves the rapid production of high-affinity antibodies by memory B cells, resulting in a more effective and long-lasting defense against the pathogen.
Secondary response: The secondary response is the immune system's faster and more effective reaction to a pathogen upon subsequent exposures. It is mediated by memory cells that were generated during the primary response.
Self-reacting B cells: Self-reacting B cells are a subset of B lymphocytes that recognize and potentially react to the body's own tissues, which can lead to autoimmune diseases if not properly regulated. Normally, these cells are eliminated or inactivated through central tolerance mechanisms during their development.
Somatic Hypermutation: Somatic hypermutation is a process that occurs in mature B lymphocytes, where the genes encoding the variable regions of antibody molecules undergo rapid, random mutations. This genetic diversification allows B cells to generate a vast array of antibodies with different antigen-binding specificities, enhancing the immune system's ability to recognize and respond to a wide range of pathogens.
T cell-independent activation: T cell-independent activation occurs when B cells are activated without the aid of T helper cells. This process is typically triggered by antigens with repetitive structures, such as polysaccharides.
T-cell receptors (TCRs): T-cell receptors (TCRs) are specialized proteins found on the surface of T cells, a type of lymphocyte that plays a crucial role in the adaptive immune response. TCRs are responsible for recognizing and binding to specific antigens presented by other cells, initiating a series of signaling cascades that activate the T cell and coordinate the immune response.
T-dependent antigens: T-dependent antigens are antigens that require assistance from T-helper cells to induce a B-cell response and the production of antibodies. These antigens typically have protein components that are presented to T-cells via MHC class II molecules.
T-dependent B cell activation: T-dependent B cell activation is a critical process in the humoral immune response, where B cells require the help of T cells to become fully activated and differentiate into antibody-secreting plasma cells. This interaction between B cells and T cells is essential for the production of high-affinity antibodies against specific antigens.
T-independent antigens: T-independent antigens are antigens that can trigger B cells to produce antibodies without the assistance of T helper cells. They typically have a repetitive structure that can cross-link B cell receptors.
T-independent B cell activation: T-independent B cell activation is a mechanism by which B cells can be activated without the need for T cell help. This process allows B cells to respond to certain types of antigens, such as bacterial polysaccharides, in a rapid and efficient manner, contributing to the humoral immune response.
Toll-like receptors (TLRs): Toll-like receptors (TLRs) are a class of pattern recognition receptors (PRRs) that play a crucial role in the innate immune response by detecting pathogen-associated molecular patterns (PAMPs) and initiating signaling cascades to activate immune cells and mount a defense against invading pathogens.
Type 1 T-independent Antigens: Type 1 T-independent antigens are a class of antigens that can stimulate B cell activation and antibody production without the need for T cell help. These antigens directly crosslink the B cell receptor, triggering a rapid and robust humoral immune response.
Type 2 T-independent Antigens: Type 2 T-independent antigens are a class of antigens that can stimulate B cell activation and antibody production without the need for T cell help. These antigens are typically large, repetitive molecules found on the surface of bacteria and viruses.
V, D, and J segments: V (Variable), D (Diversity), and J (Joining) segments are gene segments that encode the variable regions of antigen receptor genes in B cells. These segments undergo rearrangement to generate diverse antibody repertoires.
V(D)J Recombination: V(D)J recombination is a genetic process that occurs in the development of B cells and T cells, which are crucial components of the adaptive immune system. This process allows for the generation of a diverse repertoire of antigen receptors, enabling the immune system to recognize and respond to a vast array of potential pathogens.
Variable region: The variable region is the part of an antibody or T-cell receptor that varies between different antibodies or receptors and is responsible for binding to specific antigens. This variability allows the immune system to recognize a vast array of pathogens.
α chain: The α chain is a type of polypeptide chain that is a crucial component of the immunoglobulin molecule, which is the basic structural unit of antibodies. The α chain, along with the κ or λ light chain, forms the antigen-binding site of the antibody, enabling it to recognize and bind to specific target molecules or antigens.
β chain: The β chain is a type of polypeptide chain that is a critical component of the B cell receptor (BCR) and antibodies. It plays a central role in the functioning of B lymphocytes and the humoral immune response.
γ chain: The γ chain is a type of heavy chain found in certain immunoglobulin (antibody) molecules. It is a crucial component of the humoral immune response, responsible for the production and function of antibodies that can recognize and neutralize foreign pathogens.
δ chain: The δ chain is a type of heavy chain found in a subset of T cell receptors (TCRs) that are expressed on a specialized population of T cells known as γδ T cells. The δ chain, along with the γ chain, forms the TCR complex that allows γδ T cells to recognize and respond to a variety of antigens.
Affinity maturation
See definition

Affinity maturation is the process by which B cells produce antibodies with increased binding affinity for their specific antigen during an immune response. It occurs primarily in the germinal centers of lymph nodes.

Term 1 of 102

Affinity maturation
See definition

Affinity maturation is the process by which B cells produce antibodies with increased binding affinity for their specific antigen during an immune response. It occurs primarily in the germinal centers of lymph nodes.

Term 1 of 102



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AP® and SAT® are trademarks registered by the College Board, which is not affiliated with, and does not endorse this website.
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