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Old 04-23-2015
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Default immunology question, please help

Pathoma says: Th1 cells secretes IL-2 which works as a 2nd signal for the activation of Cytotoxic T cell(CD8 T Cell)
FA 2015 says: IL-2 is secreted by all T-cells, and the 2nd signal for Cytotoxic cell(CD8 Tcell) is binding between CD28 and B7.
so which one is correct? which one to follow?

another thing, Pathoma only says that binding between CD28 and B7 is 2nd signal for activation of Th Cells.
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Old 04-23-2015
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Quote:
Originally Posted by drjgsu View Post
Pathoma says: Th1 cells secretes IL-2 which works as a 2nd signal for the activation of Cytotoxic T cell(CD8 T Cell)
FA 2015 says: IL-2 is secreted by all T-cells, and the 2nd signal for Cytotoxic cell(CD8 Tcell) is binding between CD28 and B7.
so which one is correct? which one to follow?

another thing, Pathoma only says that binding between CD28 and B7 is 2nd signal for activation of Th Cells.
I will go with what pathoma says because the same is given in Review of Medical Microbiology & Immunology - Levinson
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Old 04-23-2015
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Quote:
Originally Posted by drjgsu View Post
Pathoma says: Th1 cells secretes IL-2 which works as a 2nd signal for the activation of Cytotoxic T cell(CD8 T Cell)
FA 2015 says: IL-2 is secreted by all T-cells, and the 2nd signal for Cytotoxic cell(CD8 Tcell) is binding between CD28 and B7.
so which one is correct? which one to follow?

another thing, Pathoma only says that binding between CD28 and B7 is 2nd signal for activation of Th Cells.

When they talk about "second signal" in FA, they mean once there is a link between APC and Th1 cells. First signal is the binding of the TCR with the MHC-II, second signal is the costimulatory signal, ie: CD28/B7 binding.
Th1 will secrete IL-2 after this costimulation, which will also induce more proliferation by Th1 cell (self stimulation)
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Old 04-24-2015
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Originally Posted by gus247 View Post
When they talk about "second signal" in FA, they mean once there is a link between APC and Th1 cells. First signal is the binding of the TCR with the MHC-II, second signal is the costimulatory signal, ie: CD28/B7 binding.
Th1 will secrete IL-2 after this costimulation, which will also induce more proliferation by Th1 cell (self stimulation)
dude!!!
am talking abt the 2nd signal of CD8 cells and not CD4cells.

both FA and Pathoma say wht u have just said now(2nd signal for CD4cells i.e costimulatory signal)

but when it comes to the CD8 cells, FA and Pathoma have different views.
and i think cleverFox is right over here.

and by the way, yes IL-2 induce proliferation of Th1 cells but the main inducer is IL-12 which is secreted by Macrophages so that in return Th1 can release IFNγ for the activation of macrophages.
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Old 04-24-2015
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Quote:
Originally Posted by drjgsu View Post
Pathoma says: Th1 cells secretes IL-2 which works as a 2nd signal for the activation of Cytotoxic T cell(CD8 T Cell)
FA 2015 says: IL-2 is secreted by all T-cells, and the 2nd signal for Cytotoxic cell(CD8 Tcell) is binding between CD28 and B7.
so which one is correct? which one to follow?

another thing, Pathoma only says that binding between CD28 and B7 is 2nd signal for activation of Th Cells.
Simple version:[LIST]
-Macrophage sees pathogen, degrades it and a fragment of the pathogen is taken up to the MHC-II receptors on the macrophage.
-Macrophage presents the pathogen fragment to helper T-cells.
-Macrophage has B7 and TH1 cells have CD28. Macrophage and TH1 cells form a complex by joining their B7 and CD28 receptors.
-Once the complex is formed, macrophages release TNF-a to stimulate TH1 cells to release INF-y. This is called co-stimulation.
-Once co-stimulation occurs, TH1 cells release cytokines such as IL-2 which activates cytotoxic T-cells which then recognizes viral or tumor infected cells and kill them by binding to the MHC-I complex on the infected cells.

Remember, MHC-I is present on all nucleated cells EXCEPT for RBCs, and MHC-II is ONLY expressed on antigen presenting cells (APCs)
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