Flashcards in Mechanisms of Immunity Deck (25):
categories of pathogens?
two extremes of pathology?
bacteria that result in single toxin or attach to surface epithelial (needs antibody neutralization)
bacteria that are not toxic and cause disease by invasion of tissues (needs mediated immunity)
replicate outside host cells
innate response to extracellular bacteria?
epithelial barrier, flora
phagocytes (macs and neutros)
C3 - alternative C' > C5a C3a
may lead to clotting and fibrin formation
adaptive immune response to extracellular bacteria?
antibody production and activation CD4+
helper T cells produce cytokines for B cell response, macrophage activation, and inflammation
antibody and complement
systemic inflammatory response syndrome
what can lead to endotoxic shock?
what are the results of TNF and IL-1
cause endothelial cells to express cell adhesion molecules and thromboplastin
promote adhesion of cells and fibrin deposition
enhanced by PAF
how do gram + bacteria induce shock?
massive release of cytokines (storm) by superantigens
how to block shock?
TNF neutralizing antibody
PAF and NO inhibitors
not useful clinically (only modeled experimentally)
how do bacteria evade complement?
-outer capsule with no complement binding
-outer surface so phagocytes can't access bound C3b
-surface structures that divert the MAC away
-membrane enzymes can degrade complement
-outer membrane can resist insertion of MAC
-secrete decoy proteins that cause complement to be deposited on them and not on bacterium
how do bacteria and fungi evade phagocyte killing?
-repellent or toxins that inhibit chemotaxis
-capsules that inhibit phagocyte attachment
-once phagocytosed, release factors blocking killing
-catalase - breaks down H2O2
-resistant outer coats
-lipoarbinomannan - block ability of macrophages to respond to IFN-gamma
-impair antigen presenting function
-escape phagosome and multiple in cytoplasm
-organism can kill phagocyte via necrosis or apoptosis
-blebs membrane to soak up antibody
-LPS is sialylated
-phase variation - alternative set of surface molecules
-genes for pilus under go recombination
innate immune response to intracellular bacteria?
phagocytes, NK cells, IL-12, IFN-gamma
adaptive immune response to intracellular bacteria?
T cells activate phagocytes to eliminate the microbes
cytokines and intracellular bacteria
IL-12 knockout reduce ability to control bacterial growth
IFN-gamma knockout cannot control growth
innate immunity can control what?
bacterial growth and spread
but elimination requires CD4 and CD8 response
dendritic cells can display virally infected cells to CTLs and T helper cells
collection of macrophages that fuse to form multinucleated giant cell
haemophilus influenza type B (HiB)
encapsulated Gram - rod bacteria
innate viral immunity?
IFNs and NK cells
adaptive viral immunity?
antibodies, CTLs, CD8, phagocytosis