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103 Cards in this Set
- Front
- Back
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Lymphocytes arise from the same stem cells but differentiate into two distinct cell types. What are they? What are their maturity sites?
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B cells mature in specialized bone marrow.
T cells mature in the thymus gland. |
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Where do mature cells settle and what is their role?
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Mature cells settle in lymphoid organs and serve as a constant attack force for infectious agents.
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What are antigens?
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molecules that are recognized and engulfed by dendritic cells, macrophages, or B cells.
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Where are antigens processed?
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Antigens are processed by antigen-presenting cells (Macrophages, Dendritic cells, and, B cells) The APC then presents it to the T cell, which stimulates other B and T cells.
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What is the relationship between B cells and T cells?
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Most B cells require stimulation from T cells in order to become active.
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What are memory cells and where do they come from?
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Memory cells act as rapid recall of the antigen for future infection. They come from B cells that have been activated by T helper cells and have undergone a spurt of cell division. During this cell division, plasma cells are also created which secrete antibodies (proteins).
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What two types of cells differentiate from B cells?
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Plasma cells (which make antibodies) and Memory cells (rapid recall of antigen)
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What is meant by "humoral immunity"? "Cell-mediated immunity"?
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HUMORAL: Antibodies circulate in fluids (blood, ECF, and lymph). The antibodies react spcifically with the antigen and mark it for an enhanced response.
CELL-MEDIATED: T-cells act out cell-mediated immunity because they act directly against any cells bearing an antigen (no marking or signaling, just destruction). |
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Which cells synthesize cytokines?
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T-cells
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What are the major functions of receptors?
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* to perceive and attach to nonself or foreign antigens
* to promote recognition of self antigens * to receive and transmit chemical messages among other cells of the system * to aid in cellular development |
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What is meant by MHC?
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MHC is the major histocompatibility complex. It refers to one set of genes that codes for human cell receptors and gives rise to a series of glycoproteins (MHC molecules) found on all human cells except RBCs
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What is HLA?
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HLA means human leukocye antigen. It is a receptor complex that plays a vital role in recognition of "self" by the immune system and in rejection of transplanted tissues.
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What are the two MHC groups and their respective roles?
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CLASS I MHC genes code for markers that display unique characteristics of self and allow for the recognition of self molecules and the regulation of immune reactions.
CLASS II MHC genes code for immune regulatory recptors and are grouped togetehr as antigen-presenting cells (APCs)--includes macrophages, dendritic cells, and B cells. |
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What is the general "rule" regarding genetics and MHC?
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The pattern is relatively predictable. The closer the relationship, the greater the probability for similarity in MHC profiles.
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T or F. Some humans express molecules that are identical, therefore compatible with other humans.
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False. Even closely related humans express molecules that are antigenic to eachother. This is where testing for MHC and antigens is necessary in organ transplants and blood transfusions.
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B cell receptors bind to __________ while T cell receptors bind to ____________ and ____________.
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B cells----Free antigens
T cells----Processed antigens and MHC molecules |
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Where are antigens found?
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Everywhere, from microorganisms to chemical compounds.
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Explain the clonal selection theory of lymphocite development and diversity.
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ANTIGEN-INDEPENDENT:
1. Stem cell undergoes rapid cell division---->numerous progeny. Cell differentiation and random rearrangments lead to clones, each bearing a different receptor. 2. lymphocyte clones that cary specificity for self molecules that could be harmful are destroyed. 3. Specificity for a single antigen molecule is programmed into lymphocyte and set for the life of the clone. The mature but naive lymphocytes are ready for differentiation under stimulation of certain organs and immune reactions. ANTIGEN-DEPENDENT: 4. Lymphocytes populate lymph organs, encounter antigens, which stimulate the final activation and immune function. Antigens select only clones that carry matching receptors. |
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What are immunoglobulins?
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Large glycoprotein molecules that serve as specific receptors of B cells and as antibodies.
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Describe immunoglobulin molecules.
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A composite of 4 polypeptide chains: 2 identical heavy (H) chains and 2 identical light (L) chains. Each light chain binds to a heavy chain and the two heavy chains bind to eachother with DISULFIDE bonds, creating a Y-shape.
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The embryonic yolk sac, the liver, and the bone marrow are sites where...
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...stem cells give rise to immature lymphocytes
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The progeny cells of a B cell clone are called....
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plasma cells
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Helper T cells...
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activate B cells and other T cells
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Plasma cells secrete...
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antibodies
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Cell surface markers involved in immune reactions....
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1. are the result of genetic expression
2. function in recognition of self molecules 3. receive and transmit chemical messages among other cells of the system 4. aid in cellular development |
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The major histocompatibility complex is...
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glycoproteins, called MHC antigens, found on all body cells except red blood cells
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Class II MHC genes code for...
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receptors located primarily on macrophages and B cells.
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Class I MHC genes code for...
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self receptors recognized by T lymphocytes.
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List 4 characteristics of Lymphocytes.
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1. possess MHC antigens for recognizing self
2. have membrane receptors that recognize foriegn antigens 3. gain tolerance to self by destruction of lymphocytes that could react against self 4. develop into clones of B and T cells with extreme variations of specificity. |
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Where are MHC antigens found?
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All cells on the body except red blood cells
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The monomer subunit of immunoglobulin molecules has...(describe the structure)
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1. two identical heavy polypeptide chains
2. two identical light polypeptide chains 3. disulfide bonds between polypeptide chains 4. a variable and constant region on each polypepetide chain |
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What is the variable region?
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The region of each antibody molecule where amino acid composition is highly varied from one clone of B lymphocytes to another.
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Lymphocyte maturation involves...
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1. hormonal signals that initiate development
2. B cells maturing in bone marrow sites 3. T cells maturing in the thymus 4. release of mature lymphocytes to begin migration to various lymphoid organs. |
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Properties of effective antigens include...
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1. foriegn to the immune system
2. molecular complexity 3. large molecules with a minimum molecular weight of 1,000 4. cells or large, complex molecules. |
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What is the antigenic determinant?
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The molecular fragment on an antigen molecule that a lymphocyte recognizes and responds to is...
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What is a hapten?
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The molecular fragment on an antigen molecule that a lymphocyte recognizes and responds to
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What are superantigens?
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bacterial toxins that activate T cells at a 100X greater rate than other antigens.
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List 4 characteristics of antigen presenting cells.
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1. include dendritic cells
2. include macrophages 3. engulf and modify antigen to be more immunogenic 4. hold and present processed antigen on their cell membrane surface. |
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T cell response to T cell dependent antigens requires;
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1. typically a protein antigen
2. binding of T cell to a class 11 MHC receptor on a macrophage 3. binding of T cell to a site on the antigen 4. interleukin-1 activating the T helper cell |
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List 4 characteristics regarding the Fc region of an immunoglobulin.
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1. Is called the crystallizable fragment
2. forms the antigen binding sites 3. contains an effector molecule that can bind to cells such as macrophages and mast cells 4. contains an effector molecule that can fix complement 5. determines the class to which the immunoglobulin belongs |
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Explain neutralization
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Which process involves antibodies covering surface receptors on a virus or toxin molecule.
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Explain agglutination
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Which process involves antibodies cross linking cells or particles into large aggregates.
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What is opsonization?
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Which process involves antibodies coating microorganisms in order to facilitate phagocytosis?
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The immunoglobin class that has a dimer form found in mucus, saliva, colostrum and other body secretions is...
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IgA
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The immunoglobulin class that is the only one capable of crossing the placenta is...
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IgG
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The immunoglobulin class that has an Fc region that binds to receptors on basophils and mast cells is;
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IgE
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Give 4 characteristics of IgM>
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1. has 10 antigen binding sites
2. contains a central J chain 3. is the first class synthesized by a plasma cell 4. is an opsonin. |
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Which immunoglobulin class/es can fix complement?
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IgM and IgG
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The immunoglobulins found on the surface of Bcells is/are...
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IgM and IgD
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List 4 characteristics of Monoclonal antibodies
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1. originate from a single B cell clone
2. have a single specifity 3. are secreted by hybridomas 4. are used in immunology lab tests and cancer therapy |
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The most significant cells in graft rejection are...
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cytotoxic T cells
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These lymphocytes lack specificity for antigen and are cells that attack cancer cells and virus infected cells.
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natural killer cells
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These cells carry CD8 receptors and function to inhibit B cells and other T cells.
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Suppressor T cells
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What role do cytotoxic T cells play?
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secrete lymphotoxins and perforins that damage target cells.
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An example of artificial passive immunity would be...
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giving a person immune serum globulins to chickenpox virus after exposure to the disease.
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An example of natural passive immunity would be...
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a fetus acquiring maternal IgG to the chickenpox virus across the placenta.
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An example of artificial active immunity would be...
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chickenpox vaccine triggers extended immunity to chickenpox
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Which cells secrete antibodies?
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Plasma cells
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The human leukocyte antigen(HLA) system functions in...
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recognition of self
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B cells bind antigens; this is true or false of specificity?
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TRUE
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MHC molecules are found on which cells?
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1. leukocytes
2. eosinophils 3. epithelial cells 4. islet of langherhans cells |
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What is immunotherapy?
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1. It uses antitoxins
2. use of immune serum globulin 3. conferring of passive immunity 4. administering of preformed antibodies |
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High titers of specific antibodies are components of...
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specific immune globulin
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Killed or inactivated vaccines are prepared by...
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treatment with formalin, heat or radiation
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Live attenuated vaccines
including the Sabin polio vaccine |
*include the measles, mumps, rubella vaccine(MMR)
*contain viable microbes that can multiply in the person *require smaller doses and fewer boosters compared to inactivated vaccines |
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Acellular vaccines and subunit vaccines...
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contain select antigenic components of a pathogen rather than whole cells or viruses
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Antitoxins...
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confer passive immunity
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Vaccinia virus is often used in the technique to make...
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Trojan horse recombinant vaccine.
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What is an adjuvant?
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It is a special binding substance that enhances immunogenicity and prolongs antigen retention at the injection site.
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IgM is the most abundant class of antibodies in serum. TRUE/FALSE
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FALSE. IgG is the most abundant.
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A hybridoma results from the fusion of a myeloma cell with a normal________ cell.
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B cell
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Each ______ fragment of an antibody molecule contains the variable regions of a heavy and light chain that folds into a groove for one antigenic determinant.
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Fab
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During presentation of APC bound antigen, macrophages secrete the cytokine,_____, that activates T helper cells.
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interleukin 1
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Class I, II, and III MHC genes are located on the ninth chromosome of humans. TRUE/FALSE
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FALSE. They are located on the sixth.
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The structural and functional differences that distinguish immunoglobulin isotypes are due to variations associated with their Fc fragments. TRUE/FALSE
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TRUE
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One plasma cell will secrete antibodies of various classes and the antibodies will all have different specificity. TRUE/FALSE
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FALSE. They will all have the same specificity.
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The albumin fraction of serum separated by electrophoresis will contain most of the antibodies. TRUE/FALSE
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TRUE
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What can be given as immunotherapy to confer artificial passive immunity?
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Gamma globulin
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What is an epitope?
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The molecule where an antibody actually attaches to the antigen.
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What is another word for the epitope?
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Antigenic determinant
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What is the function of opsinozation
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Facilitating phagocytosis by coding antibodies for specific antigens.
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What happens during nutralization?
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The antigen is prevented from attaching and basically nutralized, since it cannot attach, it cannot survive.
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What are MHC molecules made of?
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Glycoprotein
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What is a significant characteristic of class II MHC genes?
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They possess both class I and II receptors necessary for interactions with T cells.
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Where are Class I MHC molecules found? Class II?
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Class I are found on all nucleated cells; Class II are only found on some types of white blood cells
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What are the two stages of development of lymohocytes?
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Clonal deletion (deleting or silencing clones that may be harmful to self)
Clonal selection and expansion (requires stimulation by antigens) |
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What are 2 ideas that can be derived from the clonal selection theory?
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1) lymphocyte specificity is preprogrammed existing in the genetic makeup before an antigen has ever entered the tissues.
2) each generally distinct lymphocyte expresses only a single specificity and can react to only one type of antigen |
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What does a light chain consist of?
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One variable, one joining, and one constant spliced together
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What does a heavy chain consist of?
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A variable region and diversity region gene are selected from among hundreds available and spliced to one joining region and one constant region gene.
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An undifferntiated lymphocyte has how many different genes coding for the variable region of light chains and how many coding for the variable and diversity (V and D) regions of heavy chains.
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150 for V of light
250 for V and D of heavy |
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Where are CD 4 cells found? CD 8?
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CD 4--helper T cells
CD 8--cytotoxic T cells |
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What is thought to be the underlying mechanism of toxic shock syndrome?
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--super antigens that trick large numbers of T cells into releasing massive amounts of cytokines, causing blood vessel damage, toxic shock, and multi organ failure
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What are super antigens?
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--antigens found primarily in bacteria and viruses that are a form of virulence factor.
--ie: enterotoxins given off by pathogenic staphylococcus, proteins of Epstein Barr virus, toxins from Group A strep |
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Which cells are the first on site to destroy cancer cells?
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NK cells
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Why is the anamnestic response important?
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--it requires less time, less activation, and fewer signals to form plasma cells.
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What is a Fab?
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--the site where the antigen fits into the receptor of the Antibody. Varies from good fit to no fit to poor fit. Then site has a specific 3D fit and is similar to the fit of enzymes and substrates.
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What is meant by T cell dependent?
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--B cells require activation by T helper cells, the result is the APC-T cell complex
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Give examples of T cell independent molecules
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--Streptococcus pneumoniae, E. Coli, rabies, Epstein Barr
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Describe the APC-T cell complex
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--APC cells (dendritic, macrophages, B cells) recognize and attach to foreign molecules, move it to the surface of the APC where it attaches to the MHC II receptor. The T cell the attaches to both the MHC II and the antigen. --The CD4 receptor binds to the MHC of the APC, interleukin 1 is released by the APC, stimulating T helper cells which release interleukin II. Interleukin II stimulates committed B
and T cells to do more action. |
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Where is interleukin 1 produced?
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--In the APC, which stimulates T helper cells which then release interleukin 2.
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--What are the roles of lymphocytes?
--B cells? --T cells |
Lymphocytes--Surveillance and recognition
B cells--Find free antigens T cells--Find processed antigens (created/processed by by an antigen presenting cell) |
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--Name and describe two groups of MHC
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Class 1: found in cytotoxic (nucleated) t cells, required for T lymphocytes; act in self-recognition
Class 2: found in antigen presenting t cells; act in specific immune response. They are different receptors |
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--Where are MHC found?
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On host cells, specifically T cells. They display a specific characteristic as receptors for specific cells. Found on all cells except red blood cells.
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