Mechanism of Host Defense Flashcards
What are the host defenses against extracellular microbes?
Innate (phagocytes and complement)
Antibody
CD4 (Th17 and Th2)
What are the host defenses against intracellular microbes?
Innate (NK and macrophages)
CD4 (Th1)
CD8
What are the host defenses against viruses, specifically recovery from infection?
Innate (Type 1 Interferon - a-IFN and K cells
Adaptive (CTL - most important)
What are the host defense against viruses, specifically protection from re-infection or infection following vaccination?
Neutralizing antibody
What does the type of defense depend on in an infection?
Extracellular
Toxigenic
Intracellular
What is the immune defense pattern against extracellular bacteria?
Complement and antibacterial IgG > Opsonization and Acute inflammation > neutrophils > phagocytosis
In a virus infected cell, type 1 IFN does what to the cell?
Inc expression of class I MHC molecules on infected cells so CTLs (CD8) can kill it
In an uneffected cell during a viral attack, what happens when the class 1 IFN induces the antiviral state?
Induction of enzymes that block viral replication
In an infected cell, what is missing that an NK cell recognizes and why is it missing?
MHC class 1 is missing because viruses do not want cytotoxic T cells to find them via MHC
What is the attack pattern for cyotoxic T cells ?
Antigen recognition and conjugate formation > CTL activation > granule exocytosis > detachment of CTL > target death
What is the main mechanism for toxin defense?
Antibody specifically anti-toxin (neutralizing) antibody
What is the defense against and intracellular bacteria?
Bacteria infects a macrophage so Th1 cells produce gamma-IFN or seretes cc-chemokines to recruit mononuclear cells
If an infected macrophage is not “cured” what occurs?
Mononuclear cells surround infected mac because it can’t be killed and a granuloma forms
What are the defense components against extracellular fungi?
Opsonins (compliment and antibody)
Phagocytes (neurtrophil and activated macrophages)
Macrophage activation requires ____ to activate and supply ___ .
Th1, gIFN
What fungi are extracellular?
Aspergillus and Candida
If these two cells are suppressed an extremely bad extracellular fungal infection will occur.
T-cells and neutrophils
What is the intracellular fungi?
Histoplasma
What are the defense components against intracellular fungi?
Activated macrophages
require Th1 cells to supply gIFN
What is the defense pattern against extracellular protozoa (like malaria, e. histo or giardia)?
Protozoa > compliment and anti-parasite antibody > opsonization blocking antibody > phagocytosis
Does IgE work against protozoans?
No
What is the defense pattern against intracellular protozoans (like leshmania)?
Protozoa > infected macrophage > gIFN from Th1 cells or cc-chemokines to recruit mononuclear cells
What is the defense pattern against helminths?
Helminth > anti-parasite IgE . mast cell sensitization and degranulation > IL-5 > production of eosinophils in bone marrow; chemotactic factors of eosinophils
What pathogen evades phagocytosis by an anti-phagocytic capsule?
Strep pneumo
Staph aureus
GAS
Heamophilus
What pathogen evades phagocytosis by prevention of formation of phagolysosome?
Mycobacterium TB
What pathogen evades phagocytosis by escape from the phagolysosome?
Mycobacterium TB
What pathogen evades phagocytosis by resisting lysosomal enzymes?
Mycobacterium TB
What pathogen causes lysis of secretary IgA?
Neisseria
What pathogen causes antigenic variation?
HIV, influenza, T. brucei, N. gonorrhoeae
What pathogen causes enhanced antibodies which oponizes the organism which is phagocytosed by macrophages so the virus was replicate there?
HIV, Dengue
Which pathogen masks its pathogen antigen by host serum proteins?
Schistosomes
What pathogen inducts the immune system?
HIV
Which pathogens express surface molecules that bind to the Fc region oh IgG?
HSV, ZVZ, Staph aureus
Which pathogens interfere with antigen presentation by preventing peptide loading in MHC-1?
HSV, VZV
