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Old 09-19-2014
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Default confusing question in immunology!

In kaplan page 170 in chapter 14 (transplantation immunology):
Question 6:
A 6 year old from Zimbabwe is admitted to a U.S. oncology center for treatment of an advanced case of Burkitt lymphoma. Analysis of the malignant cells reveals that they are lacking MHC class 1 antigens on their surface. Which of the following cytokines produced by recombinant DNA technology could be injected into his solid tumor to increase this tumor cell's susceptibility to CD8+ mediated killing?
(A) IFN-gamma
(B) IL-1
(C) IL-2
(D) IL-10
(E) TNF-alpha

The written answer is A. Kaplan's explanation is:
IFNs of all types increase cellular expression of MHC class I and II products. Because CD8+ cells recognize their targets by MHC class I dependent mechanisms, increase in the amount of these antigens on tumor cell targets would increase susceptibility to cytotoxic killing.

My answer was (E) TNF-alpha since in page 160 in the chapter itself of kaplan book it is stated:
Interferons and TNF-alpha and beta all increase expression of class I MHC molecules in the graft, and IFN-gamma increase the expression of class II MHC as well, increasing susceptibility of cells in the graft to MHC restricted killing.

However their explanation of excluding the choice (E) contradicts the chapter saying that: TNF-alpha does not increase MHC class I molecule expression. It may act directly on tumor cells to cause their necrosis and decrease angiogenesis. It is a product of TH1 cells that stimulates the effector cells of cell mediated immunity.

I am confused
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Old 10-03-2014
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Hmm that is weird. If you read chapter 8, pg 90, the last sentence of first paragraph, you will notice that it states Interferon gamma increases the expression of MHC I molecules on target cells! Just stick with that! I read the question you posted and got the answer right straight away. Haha not bragging, just saying avoid all the unnecessary details, immunology is confusing.

There are similar questions in UW, and all of them state interferon gamma as the cytokine required to increase MHC I molecules on target cells for CD8 lymphocytes.

Good luck!
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Albatoul Khaled (10-03-2014)
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Old 10-03-2014
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Thanks a lot
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