Questions and Answers
The ability of a host to resist infection or disease is referred to as ______
immunity
Innate immunity is also known as ______ immunity.
nonspecific
An antigen can have several ______ that bind to a specific antibody.
epitopes
Antibodies are ______ that upon binding can inactivate or neutralize an antigen.
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Serum antibodies are referred to as ______.
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B cells differentiate into ______ secreting plasma cells and memory cells upon activation with an antigen.
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Lymphocytes are the major cells of the ______ immune system.
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There are two major types of lymphocytes: B cells and ______ cells.
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Antibodies can also coat bacteria and parasites to make them more readily recognized and engulfed by ______ cells.
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Each B cell expresses on its surface approximately identical ______ molecules.
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Antibodies have two identical ______ chains and two identical light chains.
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The Ab combining site for antigen is made up of amino acid residues contributed by both the ______ and L chains.
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Most classes of Abs have two combining sites for ______.
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After a B cell differentiates into a ______ cell, the secreted form of Ig is made.
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T lymphocytes destined to become T cells originate in the ______ but mature in the thymus gland.
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A type of T cell called a ______ cell is required to help B cells respond to most antigens.
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T cells recognize ______ fragments of molecules derived from a protein antigen.
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MHC class I molecules present fragments of ______ antigens generated in the cytoplasm of the cell.
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The mechanism by which a CTL distinguishes a healthy cell from an infected cell is through the ______ peptide.
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MHC Class I molecules present ______ peptides to CD8 T cells.
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T cell receptors interact with the ______ peptide as well as the MHC molecule presenting it.
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The CD4 molecule is a cell-surface receptor for the ______ Immunodeficiency Virus.
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Helper T cells express ______ molecules on their surface.
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In an ELISA, the enzyme ______ phosphatase is commonly used to give a colorimetric reaction with its substrate.
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The secondary antibody in an ELISA is covalently bound to the enzyme ______.
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The indicator o-phenylenediamine changes from ______ to yellow-brown when oxidized.
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The ______ molecule is used as a blocking agent in an ELISA to prevent non-specific binding of the antibody.
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The antiserum in an ELISA contains ______ specific for the antigen OVA.
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In mammalian hosts, this defense system can be divided into two fundamentally different, yet complementary, components called innate and adaptive ______.
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Innate immunity occurs rapidly and acts as a first line of ______.
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Adaptive immunity is acquired by the host in response to the presence of a foreign substance called a(n) ______.
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Antibodies reside in the host's _______, and serum antibodies are referred to as immunoglobulins.
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Adaptive Immunity has ______, responding faster and more effectively upon repeated exposure to foreign agents such as bacteria, viruses and toxins.
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Antibodies can directly neutralize a pathogen e.g., a virus, by preventing it from infecting cells or they can mediate the binding of other molecules such as ______ to the microbial surface causing lysis.
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B cells are produced and mature in the ______ marrow.
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Antibodies are proteins that can directly neutralize a pathogen e.g., a virus, by preventing it from infecting cells or they can mediate the binding of other molecules such as complement to the microbial surface causing ______.
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Antibodies can also coat bacteria and parasites to make them more readily recognized and engulfed by phagocytic ______
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Each B cell expresses on its surface approximately ______ identical g1 molecules
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Abs contain two identical heavy (H) ______ and two identical light (L) chains
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After a B cell differentiates into a ______ cell, the secreted form of Ig is made
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T lymphocytes destined to become T cells originate in the ______ but mature in the thymus gland
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A type of T cell called a'Thelper ______ is required to help B cells respond to most antigens
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T cells recognize short proteolytically digested ______ of molecules derived from a protein antigen
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MHC class I molecules present fragments of ______ antigens generated in the cytoplasm of the cell
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Only certain cells called professional ______ presenting cells express MHC class II molecules and process extracellular antigens
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The Ab combining site for antigen is made up of amino acid residues contributed by both the H and ______ chains
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Typical ______________ Antigen-Presenting Cell
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Different antigen processing pathways lead to the presentation of peptides on MHC class ______________ versus class II molecules
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TCell Receptors are similar in structure to surface ______________ but only have one pair of chains
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The CD4 molecule is a cell-surface receptor for the Human ______________ Virus
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Cluster of Differentiation (CD) molecules function as ______________ and co-receptors and play an important role in intercellular communication
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Helper T cells (TH) express CD4 molecules on their surface, while Cytotoxic T cells (CTLs) express CD______________ molecules
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For the first step of an ELISA, the antigen is non-specifically adsorbed to a ______________ well microtiter plate
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To detect bound Abs, secondary Abs made in another species are used that recognize the Abs being tested, and are covalently bound to an enzyme that gives a ______________ reaction with its substrate
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HRP uses the substrate hydrogen peroxide to oxidize an indicator called o-______________diamine
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Horse serum is commonly used as a ______________ agent in an ELISA to prevent non-specific binding of the antibody
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Study Notes
Immunity and Adaptive Immunity
- Immunity refers to the ability of a host to resist infection or disease
- There are two components of immunity: innate and adaptive
- Innate immunity is non-specific, acts as a first line of defense, and provides basic mechanisms to defend the host against foreign substances or agents of disease
- Adaptive immunity is acquired in response to the presence of a foreign substance called an antigen
- Antigens include microbial proteins, polysaccharides, and lipids
- Antigens have epitopes, which are regions or sites that bind to specific antibodies
Antibodies and Immunoglobulins
- Antibodies are proteins that upon binding can inactivate or neutralize an antigen
- Antibodies can directly neutralize a pathogen, or they can mediate the binding of other molecules such as complement to the microbial surface, causing lysis
- Antibodies can also coat bacteria and parasites to make them more readily recognized and engulfed by phagocytic cells, a process called opsonization
- Immunoglobulins are serum antibodies that are referred to as Ig
B Lymphocytes
- B cells are produced and mature in the bone marrow
- Upon activation with a specific antigen, B cells differentiate into antibody-secreting plasma cells and memory cells
- Each B cell expresses on its surface approximately 10^5 identical Ig molecules that differ from the secreted Ab in that they contain a transmembrane segment
- The Ab combining site for antigen is made up of amino acid residues contributed by both the H and L chains
T Lymphocytes
- Lymphocytes destined to become T lymphocytes or T cells also originate in the bone marrow but mature in the thymus gland
- T cells can remain in the thymus, circulate in the blood, or reside in lymphoid organs such as the lymph nodes and spleen
- Distinct sub-classes of T cells perform different functions
- A type of T cell called a T helper cell (T,) is required to help B cells respond to most antigens
- T, cells also produce soluble proteins called cytokines that affect B cell differentiation and the activation of other cells
- The other sub-class of T lymphocytes is the cytotoxic T cell (CTL), which can directly kill cells that have been infected with an organism
Antigen Recognition by B and T Lymphocytes
- B cells recognize intact pathogenic organisms, and the antibodies produced generally bind surface molecules of the pathogens in their native conformation
- T cells recognize short, proteolytically digested fragments of molecules derived from a protein antigen, presented on the surface of cells in association with major histocompatibility complex (MHC) molecules
Antigen Processing and Presentation
- Antigens are degraded in cells by mechanisms referred to as "antigen processing"
- Antigens taken up from outside the cell are phagocytosed by macrophages and degraded in phagolysosomes
- The resulting fragments of the antigen are then presented at the surface in association with MHC class II molecules for recognition by T, cells
- Only certain cells called professional antigen-presenting cells (B cells, macrophages, and dendritic cells) express MHC class II molecules and process extracellular antigens taken up from outside the cell for T, cell recognition
T Cell Receptors
- Both T, cells and CTLs express on their surface approximately 10^5 identical receptors that are specific for a particular peptide-MHC molecule complex
- These receptors, called "TCRs or T cell receptors," interact with the antigenic peptide as well as the MHC molecule presenting it
- TCRs are similar in structure to surface Ig but only have one pair of chains (aß) and thus, only one combining site for the antigenic peptide-MHC molecule complex
Immunity and Adaptive Immunity
- Immunity refers to the ability of a host to resist infection or disease
- There are two components of immunity: innate and adaptive
- Innate immunity is non-specific, acts as a first line of defense, and provides basic mechanisms to defend the host against foreign substances or agents of disease
- Adaptive immunity is acquired in response to the presence of a foreign substance called an antigen
- Antigens include microbial proteins, polysaccharides, and lipids
- Antigens have epitopes, which are regions or sites that bind to specific antibodies
Antibodies and Immunoglobulins
- Antibodies are proteins that upon binding can inactivate or neutralize an antigen
- Antibodies can directly neutralize a pathogen, or they can mediate the binding of other molecules such as complement to the microbial surface, causing lysis
- Antibodies can also coat bacteria and parasites to make them more readily recognized and engulfed by phagocytic cells, a process called opsonization
- Immunoglobulins are serum antibodies that are referred to as Ig
B Lymphocytes
- B cells are produced and mature in the bone marrow
- Upon activation with a specific antigen, B cells differentiate into antibody-secreting plasma cells and memory cells
- Each B cell expresses on its surface approximately 10^5 identical Ig molecules that differ from the secreted Ab in that they contain a transmembrane segment
- The Ab combining site for antigen is made up of amino acid residues contributed by both the H and L chains
T Lymphocytes
- Lymphocytes destined to become T lymphocytes or T cells also originate in the bone marrow but mature in the thymus gland
- T cells can remain in the thymus, circulate in the blood, or reside in lymphoid organs such as the lymph nodes and spleen
- Distinct sub-classes of T cells perform different functions
- A type of T cell called a T helper cell (T,) is required to help B cells respond to most antigens
- T, cells also produce soluble proteins called cytokines that affect B cell differentiation and the activation of other cells
- The other sub-class of T lymphocytes is the cytotoxic T cell (CTL), which can directly kill cells that have been infected with an organism
Antigen Recognition by B and T Lymphocytes
- B cells recognize intact pathogenic organisms, and the antibodies produced generally bind surface molecules of the pathogens in their native conformation
- T cells recognize short, proteolytically digested fragments of molecules derived from a protein antigen, presented on the surface of cells in association with major histocompatibility complex (MHC) molecules
Antigen Processing and Presentation
- Antigens are degraded in cells by mechanisms referred to as "antigen processing"
- Antigens taken up from outside the cell are phagocytosed by macrophages and degraded in phagolysosomes
- The resulting fragments of the antigen are then presented at the surface in association with MHC class II molecules for recognition by T, cells
- Only certain cells called professional antigen-presenting cells (B cells, macrophages, and dendritic cells) express MHC class II molecules and process extracellular antigens taken up from outside the cell for T, cell recognition
T Cell Receptors
- Both T, cells and CTLs express on their surface approximately 10^5 identical receptors that are specific for a particular peptide-MHC molecule complex
- These receptors, called "TCRs or T cell receptors," interact with the antigenic peptide as well as the MHC molecule presenting it
- TCRs are similar in structure to surface Ig but only have one pair of chains (aß) and thus, only one combining site for the antigenic peptide-MHC molecule complex
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Description
Learn about immunity, its types, and how B and T lymphocytes recognize antigens in the human body. Explore the differences between innate and adaptive immunity.
