Flashcards in Pathology - L1 - Immunologic Diseases Deck (48)
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antigen
any substance able to induce a specific immune response
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B-lymphocyte functions?
neutralizes microbes, phagocytosis, complement activation
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where are B-cells found?
in lymphoid follicles of lymph nodes, bone marrow, and extranodal lymphatic tissue (i.e. tonsils, appendix, Peyer's patch)
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types of T lymphocytes?
helper, cytotoxic, regulatory
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helper T-cells functions?
activation of mac's, in inflamm, activation (proliferation & differentiation) of T & B lymphocytes
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Cytotoxic T lymphocyte function?
killing of infected cell or cells harboring microbes
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regulatory T lymphocyte function?
suppression of immune response
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where are 60-70% of circulating lymphocytes found?
in thymus and paracortical areas of lymph nodes.
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60% of lymphocytes have what ?
CD4+ marker; so they are T-helper cells
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T-helper cells regulate T and B cell rxns by secretion of _____.
cytokines
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30% of circulating lymphocytes have ____. What cells are these?
CD8+ marker; = cytotoxic T-cells (kill cells harboring microbes).
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To respond, T cells must have what?
the antigen presented by antigen-presenting cells (APC).
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APCs express what molecules?
major histocompatibility molecules (MHC)
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T-helper lymphocytes recognized antigens expressed on ____ molecules, whereas cytotoxic lymphocytes recognized antigens expressed on ____ molecules.
class II MHC; class I MHC
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antibody-dependent cell-mediated cytotoxicity (ADCC)
- mechanism of cell-mediated immune defense whereby an effector cell of the immune system actively lyses a target cell, whose membrane-surface antigens have been bound by specific antibodies.
- one of the mechanisms through which antibodies, as part of the humoral immune response, can act to limit and contain infection.
- Classical ADCC is mediated by natural killer (NK) cells; macrophages, neutrophils and eosinophils can also mediate ADCC.
- ADCC is part of the adaptive immune response due to its dependence on a prior antibody response.
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natural killer cells make what % of blood lymphocytes?
10-15%
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Natural killer cells ?
- have no T-cell markers or Ab production
- lyse tumor cells or infected cells w/o previous sensitization
- 1st line of defense against some tumors & viruses
-also can lead to AB-dependent cell-mediated cytotoxicity (ADCC)
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function of macrophages?
1) required to process and "present" antigens to lymphocytes;
2) effectors of cell-mediated immunity; produce cytokines influencing growth and function of lymphocytes, inflammation, fibroblast proliferation, and collagen deposition;
3) Phagocytic in response to T-cell activation or opsonization.
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members of the macrophage family, although weakly phagocytic?
dendritic cells (in lymphoid tissue); Langerhans cell (in epidermis, oral mucosa)
- important for presenting antigens
-also produce anti-viral cytokines
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Ag-Ab activates what...?
9 sequential components aka complement
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Complement activates ?
- anaphylaxis (i.e. c3a, c5a)
- chemotaxis (c5a)
- opsoninization (c3b)
- lysis of cells (MAC)
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what are cytokines of innate immunity?
intercellular mediators produced in response to microbes and other stimuli and mediate inflammation and anti-viral defense (TNF, IL-1, type 1 IFNs)
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functions of cytokines of adaptive immunity?
promote lymphocyte proliferation and differentiation and to activate effector cells (IL-2, IFN-y)
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____ stimulates hematopoiesis (colony stimulating factors).
cytokines
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innate immunity?
defense mechanisms that are present before infection (i.e. epidermis, phagocytic cells, dendritic cells, NK cells)
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adaptive immunity?
- lymphocytes and their products
- humoral vs cell-mediated
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humoral immunity?
- associated w/ AB production\
- B lymphocytes and ABs play predominant role
- AB (IgA, IgE, IgG, IgM) act on Ags, resulting in neutralization, lysis, phagocytosis.
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cell-mediated immunity?
- cellular neutralization of Ags
- predominant role is played by T-lymphocytes
- Ags are destroyed by lymphocytes, macrophages, etc directly or via cytokines
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X-Linked Agammaglobulinemia?
aka Bruton Disease
- failure of pre-B cells to differentiate into B cells
- Ig molecules are not assembled due to failure of light chain production
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