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33 Cards in this Set
- Front
- Back
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what is the definition of an antigen?
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any molecule that stimulates the immue system is considered an antigen; eg. proteins, sugars, nucleic acids, dust, pollen, pathogen
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what is an epitope?
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the specific region of an antigen that binds the immunoreceptor; an antigen can have multiple epitopes
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what types of immune cells are found with cellular immunity (cell mediated immunity)?
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T-cells: secreted and/or cell surface molecules provide signals for the maturation/differentiation of other leukocytes
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what are the cells assocated with
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B-cells: antibody/ Ig Targets cells/molecules for removal
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where do all immune cells come from and where do they mature?
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all cells are from hematopoietic lineage in bone marrow; T-cells= thymus; B-cells= bone marrow
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what are antigen presenting cells?
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macrophages, dendritic cells, epithelial cells, B-cells, etc???
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what is primary or central lymphoid tissue?
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sites where lymphocytes develop and mature; t-cells develop in the thymus; b-cells develop in the bone marrow
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what is secondary lymphoid tissue?
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distributed thoughout the body and are sites where NAIVE lymphocytes encounter antigen and become activated: lymph nodes, spleen, adenoids, tonsils, peyer's patch, appendix
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what are lymphoid tissues/organs?
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adenoid, tonsil, right subclavian vein, lymph node, appendix, lymphatics, left subclavian vein, thymus, heart, thoracic duct, spleen, peyer's patch (small intestine), large intestine, bone marrow
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how do antigens get to secondary lymphoid tissue?
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antigens are carried to the naive lymphocytes in secondary lymphoid tissue via the lymphatics (associated with phagocytes/dendritic cells)
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where are lymph nodes?
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lymph nodes lie at the jxns of lymphatic vessels, which collect extracellular fluid (lymph) from the tissues; antigens found in the tissues are eventually carried to lymph nodes
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how do pathogens, antigens, and dendritic cells arrive at lymph nodes?
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via the afferent lymphatic vessels
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where are mostly T cells found in the lymph node?
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paracortical areas
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where are mostly B cells found in the lymph node?
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germinal centers?? follicles surrounding germinal center???
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what are the functions of the spleen?
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1. a site of lymphocyte activation for blood-borne antigens 2. storage of immune memory (memory lymphocytes)
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where do you find IgA?
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mucosal-associated lymphoid tissue: GALT= gut-associated lymphoid tissue: tonsils, adenoids, appendix, peyer's patches & BALT= bronchial associated lymphoid tissues: lymphoid tissues that line the respiratory tract
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can antibodies that are made during a measles virus infection be used during an infection with influenza virus?
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no- Ig/T-cell receptors are highly specific for a given antigen (Angigen and Epitope)
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where does the specificity of the immune response come from?
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specificity of the immune response resides in receptors: T-cell receptor recognizes peptide associated with MHC molecule; B-cell receptor (surface immunoglobulin) recognizes antigen
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what is the composition of the immunoglobulin molecule?
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two pairs of chains: heavy and light, each of which can be divided into domains based on sequence similarity: Variable region and Constant region
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what defines antigenic specificity?
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the hypervariable domains which are located in each variable region
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where do antigens bind on the immunoreceptor?
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antigens bind in the pockets of the hypervariable regions of each arm of the immunoreceptor
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what is clonal selection?
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leads to expansion of antigen-specific and pathogen-specific lymphocytes
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what are the steps that lead to diversity of receptor specificity (clonal selection)?
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1. each lymphocyte bears a single type of receptor of a unique specificity 2. interaction betweena foreign molecule and a lymphocyte receptor leads to lymphocyte activation 3. activated lymphocytes will bear receptors of identical specificity to those of parental cell. 4. Lymphocytes bearing receptors for self molecules are delected at an early stage in lymphoid cell development
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what do B-cells recognize?
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B-cells produce antibodies that can recognize native or denatured molecules
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what do T-cells recognize?
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the T-cell antigen receptor cannot recognize intact protein antigens, but respond to peptide fragments bound to the MHC surface of another cell= antigen presenting cell
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what to classical T-cells respond to?
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response is toa peptide bound to a MHC molecule displayed on the surface of another cell, called an antigen presenting cell
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what are MCH class I molecules?
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expressed on the surface of ALL nucleated cells; recognized by T-cell receptors of cytotoxic T-cells; CD8 binds; source of peptide is CYTOPLASM
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what are MCH class II molecules?
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expressed on the surface of SOME nucleated cells, mainly antigen presenting cells (APCs); recognized by TCR of T-helper cells; CD4 binds; source of peptide is phagosome
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if a virus infects a cell, what type of MHC class molecule will bind to viral proteins in the cytoplasm?
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peptide fragments of viral proteins bind with MHC class I in ER. Bound peptides transported by MHC class I to cell surface--> cytotoxic T-cell recognizes complex of viral peptide with MHC class I and kills infected cell
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if a macrophage engulfs and degrades bacterium, producing peptides, what kind of MHC class molecule will bind and what happens next?
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Bacterial peptides will be bound by MHC class II in vescicle; bacterial peptides transported by MHC class II to cell surface; TH1 cell recognizes the complex of peptide antigen with MHC class II and activates macrophage.
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if a cell-surface immunoglobulin of a B cell binds bacteria and engulfs and degrades them, producing peptides, what kind of MHC molecule will bind?
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Bacterial peptides will be bound by MHC class II in vescicle; bound bacterial peptides transported by MHC class II to cell surface; TH2 cell recognizes the complex of peptide antigen with MHC class II and activates B cells.
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which immune responses are not advantageous to the host?
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Allergy, autoimmune and graft rejection; all are mediated by the adaptive immune system
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what is the interaction between the innate and adaptive immune response?
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1. microbes enter through break in skin and are phagocytosed by dendritic cell 2. dendritic cell matures and carries microbial antigens to local lymph nodes to become an antigen presenting cell 3. antigen-presenting cell activates T-cells to respond to microbial antigens 4. activated T-cells migrate to site of infection to eliminate residual microbes
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