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43 Cards in this Set
- Front
- Back
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Does the activation of the complement system require antibodies when the alternative and MBL pathways are triggered?
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No
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What provides the first line of humoral immunity against pathogens?
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The alternative C' pathway
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Does the alternative pathway require antibodies to be triggered?
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No
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What subunits of C3 are formed after it is cleaved?
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C3a and C3b
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What happens when C3 is cleaved into C3a and C3b?
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Recruitment of inflammatory cells, opsonization of pathogens (facilitating uptake and killing by phagocytes) and perforation of pathogen cell membranes
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Define opsonization.
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process by which a pathogen is marked for ingestion and destruction by a phagocyte
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What is the first step in activation of the alternative complement pathway?
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when C3 is cleaved to C3b, it binds factor B, which activates factor D
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What is the second step in activation of the alternative complement pathway?
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Factor B binds to C3b on microbial cell surfaces.
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What is the third step in activation of the alternative complement pathway?
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Factor D cleaves factor B/C3b to Bb/C3b => then activates the remaider of C' pathway
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Which C' components form a membrane disrupting pore in the pathogen cell surface?
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C5 -> C9
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What is the purpose of factor P in the regulation of the alternative complement pathway?
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To stabilize the Bb/C3b complex
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What are two examples of potent anaphylotoxins?
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C3a and C5
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What is the most numerous WBC?
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Neutrophils (40-70%)
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What function do neutrophils have in fighting infection?
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Phagocytic function only.
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What is an increase in the number of immature neutrophils a sign of?
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Infection (known as a "left shift")
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What directs neutrophils to the site of infection?
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Interactions between adhesion molecules
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What molecules are involved in neutrophil rolling?
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Selectins (endothelium) and addresins (leukocytes)
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What molecules are involved in tight binding of neutrophils?
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ICAMs and integrins (both leukocytes and endothelial cells)
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What molecules are involved in diapedesis of neutrophils (passage through endothelium)?
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chemokines
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What molecules are involved in the migration of neutrophils (entry into tissues proper)?
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chemokines
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What are the four key adhesion molecules?
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addressin, selectin, integrin and ICAM-1 (immunoglobulin-like molecule)
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What do phagocytes produce upon ingestion of micro-organisms?
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bacteriocidal agents
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What kills bacteria that are ingulfed by phagocytes?
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respiratory burst - formation of superoxide and hydrogen peroxide
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What do innate immune mechanisms establish at sites of infection?
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a state of inflammation
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What is released from macrophages when the come in contact with a pathogen?
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pre-inflammatory cytokines (IL-6, TNF-alpha, IL-1beta, CXCL8, IL-12)
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What are the effects of inflammatory cytokines on the liver?
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Acute-phase proteins => activation of complement opsonization => phagocytosis
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What are the effects of inflammatory cytokines on the bone marrow endothelium?
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neutrophil mobilization => phagocytosis
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What are the effects of inflammatory cytokines on the hyopthalamus?
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increased body temperature => decreased viral and bacterial replication
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What are the effects of inflammatory cytokines on fat and muscle?
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protein and energy mobilization to generate increased body temperature => decreased viral and bacterial replication
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Describe what happens during a local infection with gram-negative bacteria?
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Macropahges are activated to secrete TNF-alpha in the tissue. Increased release of plasma proteins into the tissue. Increased phatocyte and lymphocyte migration into tissue. Increased platelet adhesion to blood vessel wall. Phagocytosis of bacteria. Local vessel occlusion. Containment of infection. Antigens drain or are carried to local lymph node.
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Describe what happens during a systematic infection with gram-negative bacteria?
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Macrophages are activated in the liver and spleen to secrete TNF-alpha into the bloodstream. Systemic edema causes decreased blood volume, hyperproteinemia, neutropenia followed by neutrophilia. Decreased blood volume causes collapse of vessels. Disseminated intravascular coagulation leads to wasting and multiple organ failure: septic shock
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What is a classic sign of acute infection?
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acute phase proteins (part of the innate immune response)
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What are five examples of acute phase proteins?
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c-reactive protein, fibrinogen, MBL, alpha1-antitrypsin and serum amyloid A
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What is increased erythrocyte sedimentation rate a marker of?
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inflammation
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What are classic clinincal signs of immunological events occuring?
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Heat, redness, pain and swelling (Calor, Rubor, Dolor and Tumor)
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What is the job of Type I Interferons?
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to inhibit viral replication (degradation of viral RNA) and activate host-defense responses
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Are Natural Killer Cells able to kill virus infected cells without prior exposure?
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Yes (unlike T cells)
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Do Natural Killer cells underto TcR or Ig rearrangement?
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NO
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Describe the effectiveness of antibodies relative to different pathogens.
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Antibodies are highly specific for the pathogen that was present during their creation. They are not specific to other pathogens.
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What type of molecule do antibodies and B cells recognize?
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native protein antigens on the pathogen
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How do pathogens effect antigen-specific T and B cells?
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They drive the activation and selection of these cells but NOT the initial development.
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Describe the role of cytokine receptors.
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they bind cytokines. Deliver activation, growth and differentiation signals (some are inhibitory). They are the target of biologic therapeutics.
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Describe the role of chemokine receptors.
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Bind chemokines. Can trigger movement towards a site OR keep cells at a site.
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