L23-Immune responses against intracellular bacterial infections Flashcards
What are the primary effector cells against pathogens that replicate intracellularly?
Monocytes and macrophages
How do intracellular bacteria often enter into a cell?
They use the macrophages phagocytosis to get into the cell and then evade the killing mechanisms so they can reproduce inside the cell
Which cells help to combat intracellular pathogens?
CD8 cytotoxic T cells
How are T cells primed?
Dendritic cells present peptides and release key cytokines IL12 and IL18 which prime T cells
How do Th1 cells help the immune response?
They release IFN and TNF which activates macrophages to kill pathogens. It also overcomes the pathogen induced block and allows macrophages to kill pathogens in the phagolysosomes.
What are two killing enzymes released by cytotoxic CD8 T cells and how do they work?
Perforin - perforates the cell membrane
Granzyme - degrades host cell proteins and induces apoptosis
What is a delayed type hypersensitivity reaction?
When an infection or antigen persists resulting in an exaggerated cell mediated response which can potentially damage tissues.
What type of allergy are delayed type hypersensitivity reactions responsible for?
Type IV allergy which are responsible for contact dermatitis
How does granuloma formation occur?
When a chronic infection has caused a delayed type hypersensitivity reaction and cannot be eliminated. This results in the immune system trying to wall off the chronic infection, which causes formation of this mass of granulated tissue. Walled off by fibroblasts however this can cause a lack of organ function.
How are granulomas classified?
Into infectious (presence of lymphocytes) Or non-infectious
