L9 - Phagocytosis and Cytokines Flashcards
functions of phagocytes
- recognize
- contain
- destroy
methods by which phagocytes recognize pathogens
pattern recognition, complement, Fc receptors
Toll-like receptor (TLR)
recognize LPS via association with CD14; expressed in both endosomes and on cell surface
NOD-like receptors (NLRs)
cytoplasmic receptors that recognize peptidoglycan layer of bacteria
RIG-I-like receptors (RLRs)
recognize viral nucleic acids and induce interferon I production
types of phagocytes
neutrophils, monocytes/macrophages, dendritic cells
phagocyte recruitment and activation
- attachment - leukocytes “roll” along endothelium due to interactions between sialyl-Lewis on leukocytes and E/P selectins on endothelium
- activation - activating signals increase lymphocytic expression of integrins, which bind to ICAMs on endothelium
- diapedesis
- migration - chemokines (IL-8) lead the leukocyte to the site of infection
IL-1
key mediator of initiating fever
IL-6
cytokine that activates acute phase response
IL-8
cytokine that serves as a chemotactic factor to guide lymphocytes to site of infection
IL-12
cytokine that activates NK cells; promotes differentiation of CD4 T cells into TH1 cells
recognize LPS via association with CD14; expressed in both endosomes and on cell surface
Toll-like receptor (TLR)
cytoplasmic receptors that recognize peptidoglycan layer of bacteria
NOD-like receptors (NLRs)
recognize viral nucleic acids and induce interferon I production
RIG-I-like receptors (RLRs)
key mediator of initiating fever
IL-1
cytokine that activates acute phase response
IL-6
cytokine that serves as a chemotactic factor to guide lymphocytes to site of infection
IL-8
cytokine that activates NK cells; promotes differentiation of CD4 T cells into TH1 cells
IL-12
types of macrophage receptors
- mannose receptor (mannose in cell wall of bacteria)
- scavenger receptor (modified lipoproteins)
- CD14 (LPS receptor)
- dectins (glucans in cell wall of fungi)
- complement receptors
- Fc receptors
Chediak-Higashi syndrome
genetic defect in fusion of phagosomes and lysosomes
genetic defect in fusion of phagosomes and lysosomes
Chediak-Higashi syndrome
chronic granulamatous disease (CGD)
genetic defect in production of reactive oxygen intermediates; results in impaired killing of pathogens
genetic defect in production of reactive oxygen intermediates; results in impaired killing of pathogens
chronic granulamatous disease (CGD)
endogenous pyrogens
IL-1, IL-6, TNF-a
macrophage cytokines
- IL-1: fever
- IL-6: acute phase response
- IL-8: chemokine
- IL-12: activates NK cells; TH1 cell differentiation
- TNF-a
