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Index
»
Inflammation
»
Chapter 1
»
Neutrophils and Macrophages
level: Neutrophils and Macrophages
Questions and Answers List
level questions: Neutrophils and Macrophages
Question
Answer
Vasodilation slows blood flow in postcapillary venules and causes cells to marginate from center of flow to the periphery
Margination
Selectins on endothelial cells slow down the marginating cells
Rolling
From Weber-Palade bodies; Mediated by histamine
P-selectin
Induced by TNF and IL-1
E-selectin
Produces P-selectin and von Willebrand factor ("W"=willebrand, "P"=P-selectin)
Weber-Palade bodies
Binding site of selectins on leukocytes
Sialyl Lewis X
Firm adhesion of leukocytes on vessel wall due to interaction between CAMs and integrins
Adhesion
Intercellular/Vascular Cell Adhesion Molecule found on endothelium; upregulated by TNF and IL-1
ICAM, VCAM
Binding site of CAMs on leukocytesl upregulated by C5a and LTB4
Integrins
Autosomal recessive defect of CD 18 subunit of integrins; Manifests as delayed cord separation, increased circulating neutrophils, recurrent bacterial infection with no pus formation
Leukocyte Adhesion Deficiency
Leukocytes cross the endothelium of postcapillary venules and are attracted to chemotactic agents
Transmigration and Chemotaxis
Consumption of pathogens and necrotic tissue; Enhanced by opsonisation (IgG, C3b)
Phagocytosis
Autosomal recessive microtubule defect leading to a protein trafficking defect and impaired phagolysosome formation
Chediak Higashi Syndrome
Increased risk of pyogenic infections, neutropenia, giant granules in leukocytes, defective primary hemostasis, albinism, peripheral neuropathy
Clinical features of Chediak Higashi Syndrome
Most effective mechanism of destroying phagocytosed material
O2 dependent killing
Produces HOCl from H2O2
Myeloperoxidase
Conversion of superoxide from O2 by NADPH oxidase
Oxidative burst
Responsible for destruction of phagocytosed substance in O2 dependent killing
HOCl
Autosomal recessive or X-linked NADPH oxidase defect -> Poor O2 dependent killing
Chronic Granulomatous Disease (CGD)
Catalase positive bacteria associated with recurrent infection in CGD
Staph aureus, Pseudomonas cepacia, Serratia marcescens, Nocardia, Aspergillus
Screening test fo CGD
Nitroblue tetrazolium test
Increased risk for this infection in MPO deficiency; Generally asymptomatic
Candida infection
Enzyme in macrophage utilized in O2-independent killing
Lysozyme
Enzyme in eosinophil utilized in O2-independent killing
Major basic protein
Neutrophils undergo apoptosis within 24 hours
Resolution
Macrophages replace neutrophils and predominate
48-76 hours post-inflammation
Primary mechanism of destruction of phagocytosed materials by macrophages
O2-independent killing
Anti-inflammatory cytokines produced by macrophages for resolution and healing
IL-10, TGF-B
Cytokine produced by macrophages to recruit additional neutrophils -> persistent pus formation
IL-8
Produced by macrophages to stimulate abscess wall formation
FGF
Stimulated by macrophages through antigen presentation to CD4+ helper T cells
Chronic Inflammation