Intracellular bacteria can survive inside phagocytes but they cannot reproduce there. True or false?
False. Some can replicate inside them
Th1, CTL and circulating antibodies are common ways to eliminate intracellular bacteria. True or false?
False. Intra bacteria are inaccessible to circulating antibodies
How do NK cells and Macrophages cooperate to kill intracellular bacteria?
Macrophages eat the bacteria and produce IL-12 (or lL-15)
NK cells respond to the IL-12 by secreting IFN-gamma
IFN-gamma makes the macrophages kill the microbes
When is IL-12, IL-15 and IL-18 produced?
In response to bacteria
What does ILC1 do when it detects IL-12, IL-15 and IL-18?
It secrets IFN-gamma and TNF-alfa, which activates macrophages
Innate immunity rarely is able to eradicate intracellular bacteria. True or false?
True
What subset of T cells recognizes the antigens of ingested microbes on macrophages?
Th1 effector T lymphocytes
Both NK cells and Th1 cells secrete ______ when they detect a microbe on a _______________
IFN-gamma
Macrophage
What happens when IFN-gamma binds to a macrophage?
It starts producing microbicidal substances to kill the ingested microbe, but also secretes TNF, IL-1 and chemokines, which induce inflammation, and IL-12, which increases Th1 responses.
Why do macrophages produce TNF, IL-1 and IL-12?
TNF and IL-1: Leukocyte recruitment (inflammation)
IL-12: Th1 differentiation, IFN-gamma production
Macrophages are able to express MHC molecules and co-stimulators to further enhance T cell responses. True or false?
True
What is the basic structure of a granuloma?
It’s a compact structure with macrophages at it’s center, other cell types in the “middle” layer, and lymphocytes such as T and B cells in the outer layer
What happens if a bacteria simply decides to live inside a macrophage?
The macrophage remains active, which activates more T cells, which leads to tissue injury and a granuloma
In an intracellular infection, what does IL-10, IL-4 and IL-13 do?
Inhibit macrophage activation
Where does IL-10, IL-4 and IL-13 come from?
Th2 cells
What are some strategies intracellular bacteria have to evade the immune system?
Inhibition of phagolysosome formation
Inactivation of reactive oxygen (and nitrogen) species
Disruption of phagosome membrane (followed by escape into the cytoplasm)
Genetic defects resulting in Mendelian susceptibility to mycobacterial diseases (MSMDs) are frequently caused by defects in the genes responsible for encoding proteins related to IL-12 activation or IFN-gamma activation.
True or false?
True
