Term
| Another word for antigen? Another word for epitope? |
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Definition
-Immunogen (however, an immunogen always elicits an immune response)
-Antigenic determinant |
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Term
| About what length of molecules do B and T cell receptors bind? |
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Definition
-BCRs bind 5-6 AAs long
-TCRs bind 10-20 AAs long |
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Term
| What are haptens and why are they a problem? Give a clinical example? |
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Definition
-They are small antigens with only one epitope. This is a problem for B cells because they have to cross-link on the same antigen with two epitopes to be activated
-Normally, antigens (like bacteria) have multiple epitopes
-An example would be drug allergies, such as to penicillin. Drugs would act as haptens, but they eventually become conjugated to body proteins with the new conjugate serving as the antigen |
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Term
| How does cell rolling work? What enhances it? |
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Definition
-E-selectin molecules on the endothelium weakly binds with mucin-like cell adhesion molecules on the phagocyte
-Cytokines increase selectin expression on endothelium
-Rolling is phagocytes VS endothelium, and Vessels Select |
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Term
| What are the four steps in leading to extravasation? |
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Definition
| -Rolling, activation by chemoattractants, arrest and adhesion, transendothelial migration (extravasation) |
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Term
| What activates the rolling phagocytes? How? Result? |
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Definition
-By chemokines such as IL-8
-By compliment split protein C5a
-And by bacteria products like N-formyl peptides
-These chemoattractants trigger a G-protein mediated activation signal
-This signal induces integrins on the phagocyte to change conformation increasing affinity for Ig-CAMs |
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Term
| What mediates arrest and adhesion on phagocytes in general? Give a specific example? |
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Definition
-The activated integrins on the phagocytes bind to Ig-superfamily cellular adhesion molecules (Ig-CAMs) on the endothelial cells initiating "tight binding"
-Lymphocytes have LFA-1 (lymphocyte function-associated antigen-1) which binds to ICAM-1 (Intercellular) on the endothelium
-Lucy Found An I-CAMera |
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Term
| What is leukocyte adhesion deficiency (LAD)? Diagnosis and treatment? |
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Definition
-Leukocytes have an absent CD18 which is the β2 chain for various integrins such as LFA-1
-These individuals will have very high white cell counts
-Also have omphalitis (umbilical cord stump infection)
-Can't migrate so they do not have pus formation
-Diagnose with flow cytometry for the CD18
-Treat with bone marrow transplant |
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Term
| What are the chemoattractive molecules for for neutrophils (4)? What are the origins of those molecules? |
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Definition
-Chemokines (IL-8); produced by all immune cells but mostly macrophages
-C5a; a compliment split product
-Leukotriene B4; monocytes and macrophages, neutrophils, mast cells (rem, from arachidonic acid)
-F-met peptides; from microorganisms (we don't put the formyl group on our peptides) |
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Term
| Steps in phagocytosis (5)? |
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Definition
| -pseudopodia, formation of phagosome, fusion with lysosome to make phagolysosome, digestion, exocytosis |
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Term
| What are the major opsonizing agents for antibodies and compliment? What does it do? |
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Definition
-IgG and C3b
-The opsonization enhances adherence and phagocytosis up to 4,000-fold due to receptors for C3b and Fc (region of antibody) on the phagocytes |
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Term
| Give a clinical example where opsonization is impeded? |
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Definition
| -Protein A of Staphylococcus aureus binds to the Fc region of IgG (the major opsonizing Ig) |
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Term
| What are the two major enzymes of intracellular killing of microorganisms? Reactions? |
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Definition
-Respiratory burst activates NADPH oxidase on lysosomal membrane; 02---->02-
-The superoxide ion spontaneously goes to H2O2
-Myeloperoxidase then takes hydrogen peroxide to hypochlorite (bleach) |
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Term
| What other nonoxidative degradative contents does the lysosome have and what do they do? |
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Definition
-Lysozyme; digest cell wall
-Defensins; form channels in cell membranes
-Lactoferrin; chelates iron
-Hydrolytic enzymes |
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Term
| Chronic granulomatous disease? What kind of bacteria are they susceptible to in particular and why? What two test can we run to check for CGD? What result is abnormal? |
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Definition
-Result of NADPH oxidase deficiency
-Get recurrent bacteria and fungal infections
-Susceptible to catalase-positive organisms (catalase converts H2O2 to water and O2)
-Reason is that organisms without catalase make enough H202 for use by myeloperoxidase, so they can actually still deal with catalase negative organisms
-We can do a nitroblue tetrazolium (NBT) reduction test or a neutrophile oxidative index (NOI; a flow cytometry test) with a NEGATIVE result being abnormal |
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Term
| What are the pro-inflammatory cytokines that are initially released at the site of injury and what produces them? What are some of their actions? What protein is ultimately produced and indicative of inflammation? |
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Definition
-Macrophages in the tissue make IL-8 initially, which is a chemotactic (for migration) protein
-However, they also produce IL-1, IL-6, & TNF-α which are pro-inflammatory cytokines
-They cause temperature to raise by acting on hypothalamus, they act on bone marrow to increase cell production, they act on the liver to increase acute phase protein production such as CRP (compliment reactive protein; indicative of inflammation) |
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Term
| What proteins can cause degranulation of the mast cells? What do they release? |
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Definition
-Both C5a and C3a from compliment
-Usually requires IgE
-They release LT & PG (leukotriene & prostaglandin; both from Arac acid metabolism), and histamine |
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Term
| What are a few catalase+ microorganisms? |
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Definition
| -Staph, E. coli, aspergillus (fungi) |
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Term
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Definition
| -It is when macrophages wall off microorganisms that they cannot kill |
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Term
| What do you get with myeloperoxidase deficiency? |
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Definition
| -Candida infections (yeast) |
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