CD4 T Cell Effects (Exam 3) Flashcards
What kind of T cell is polarized and activated in response to microbes living in phagosomes of macrophages? What cytokine do they secrete?
Th1 cells
IFN-y
In response to a microbe in a phagosome of a macrophage, Th1 cells secrete IFN-y which has what effect?
activates macrophage to kill microbe
(T/F) Th1 cells directly kill microbes in phagosomes of macrophages by secreting IFN-y.
False - activate macrophage which directly kills it
Th1 cells are stimulated to respond to microbes in phagosomes of macrophages when APCs secrete what cytokine?
IL-12
What cells respond to microbes NOT in phagosomes, but are the cytoplasm of infected cells? How do they respond?
CTLs (CD8+ cytotoxic T cells)
direct killing of infected cell
What are the 3 phases of the cell-mediated immune response (T cells)?
- induction phase
- migration phase
- effector phase
In the induction phase of cell-mediated immunity, _____ present antigen to T cells which leads to their proliferation and differentiation. These cells enter ________.
APCs
circulation
During the migration phase of cell-mediated immunity, circulating T cells bind to activated _________ on endothelial cells which bring them to the infection site.
adhesion molecules
During the effector phase of cell-mediated immunity, T cells recognize specific antigen and secrete _______ which causes what response?
cytokines
activate phagocytes + inflammation
What happens to T cells which are not specific for antigen that arrive at the infection site?
return to circulation
List 2 functions of Th1.
- classical macrophage activation
- bind complement / opsonization of IgG
List 5 functions of Th2.
- produce IgE
- repair tissues
- mast cell degranulation
- barrier immunity (GI)
- activate eosinophils
In terms of Th2 and its function in GI barrier immunity, what two specific things does it do?
mucous secretion
peristalsis
Th2 functions in tissue repair via _______ macrophage activation which causes ________ and ________.
alternative
collagen synthesis
fibrosis
List 3 functions of Th17.
- activate neutrophils/inflammation
- secrete antimicrobial peptides
- increase mucosal barrier
What is the role of IL-12 in cell-mediated immunity? Which T helper cell develops?
APCs secrete IL-12 which stimulates Th1 development
What happens to T cells that recognize their specific antigen at the infection site?
retained at site to stimulate inflammation & killing of microbes
What happens to T cells which are not specific for antigen that arrive at the infection site?
return to circulation via lymphatic vessels
What is the role of CD40-CD40L?
binding –> stimulate APC to secrete IL-12 = differentiation of Th1
What is the role of IFN-y? What is it produced by?
activates macrophages to kill phagocytized microbes
produced by Th1 cells
When macrophages become activated, they produce _______ and _______ which kill the microbes in their phagosomes.
nitric oxide
lysozyme
_____ cells facilitate tissue repair by secreting ____ and ____, activating macrophages to express enzymes which promote collagen synthesis and fibrosis.
Th2
IL-4 + IL-13
What happens when activated macrophages cannot eradicate an infection?
continued cytokine and GF production –> tissue injury –> fibrosis
What is the hallmark of chronic delayed type of hypersensitivity reactions or DTH?
fibrosis
When macrophages cannot eradicate an infection, chronic cytokine signals cause macrophages to take on appearance of ______ cells and fuse to make ________ cells.
skin epithelial cells
multinucleated giant cells
Term for nodules of inflammatory tissue created by chronically activated macrophage clusters when an infection cannot be eradicated.
granulomas
What immune response is predominant in helminth infections?
Th2 effector T cell response
Of the Th2 effector T cell response to helminth infection, ___ and ___ cytokines produce IgE and ____ activates eosinophils which bind to the worm to release granules and destroy its integument.
IL-4 + IL-13
IL-5
What are 2 types of memory T cells?
central memory T cells
effector memory T cells
Where do central memory T cells go? Effector memory T cells?
central: lymph nodes
effector: peripheral tissues
Match each to the appropriate memory T cell type:
- immediate vs. limited effector functions
- rapid proliferation vs. no proliferation
Central: limited effector function, rapid proliferation
Effector: immediate effector function, no proliferation
