[khanar]

A 40 year old man is scheduled for a kidney allograft. His lymphocytes (with thymidine incorporation value of 425/cpm) are examined by the mixed lymphocytes reaction with killed stimulator cells from himself and from each of 5 prospective donors. A donor with which of the following thymidine incorporation value (cpm) will be most compatible?

A- 312
B- 1532
C- 2510
D- 15,390
E- 27,482

 

[khanar]

What is this? Never heard of it

 

[bianca]

Possible A, 'cos that which is lower than his.

 

[khanar]

What's Thymidine Incorporation Value?

Possible A, 'cos that which is lower than his.

Yea, but do you have any idea what's thymidine incorporation value? I Googled it and found nothing

 

[ClockworkDoc]

Yea, but do you have any idea what's thymidine incorporation value? I Googled it and found nothing

Thymidine incorporation value is an indicator of immunogenicity. The higher the uptake, the more the pt's wbc's are gobbling up the transplant patient's thymidine.

 

[Seetal]

Thymidine incorporation value is an indicator of immunogenicity. The higher the uptake, the more the pt's wbc's are gobbling up the transplant patient's thymidine.

oh so does that mean we have to a thymidine incorporation value that is higher than the ptt's? what's the answer then? how much higher? or is it that the ptt's WBCs are MEANT to gobble up the donor's WBCs?

 

[Devowho]

Classically, T cell alloreactivity has been measured in vitro using 3H-thymidine incorporation to assess T cell proliferation in the mixed lymphocyte reaction (MLR)...lower Tcell reaction, better tolerance no?

 

[ashishkabir]

Do you guys know where this question came from? I'm wondering if there are any other similar questions...

 

[drahmednawaz]

mixed lymphocyte reaction (MLR)

In this test, "stimulator" lymphocytes from a potential donor are first killed by irradiation and then mixed with live "responder" lymphocytes from the recipient; the mixture is incubated in cell culture to permit DNA synthesis, which is measured by incorporation of tritiated thymidine. The greater the amount of DNA synthesis in the responder cells, the more foreign are the class II MHC proteins of the donor cells. A large amount of DNA synthesis indicates an unsatisfactory "match"; i.e., donor and recipient class II (HLA-D) MHC proteins are not similar, and the graft is likely to be rejected. The best donor is, therefore, the person whose cells stimulated the incorporation of the least amount of tritiated thymidine in the recipient cells.

 

[drahmednawaz]

Hey guys! be careful; answer is b. his baseline line thymidine incorporation value is 425/cpm. if we mix dead donor cells, it is going to increase, not decrease. if the donor was a perfect match, then the answer would have been 425/cpm. cells don't respond. without a perfect match, recipient cells has to show some reaction and a value that is higher than baseline.

 

[drarnab]

Hey guys! be careful; answer is b. his baseline line thymidine incorporation value is 425/cpm. if we mix dead donor cells, it is going to increase, not decrease. if the donor was a perfect match, then the answer would have been 425/cpm. cells don't respond. without a perfect match, recipient cells has to show some reaction and a value that is higher than baseline.

i got this right and the answer was A ! they mention clearly about the donor with the thymidine value - hence they are referring to the opposite reaction.

 

[drarnab]

oh so does that mean we have to a thymidine incorporation value that is higher than the ptt's? what's the answer then? how much higher? or is it that the ptt's WBCs are MEANT to gobble up the donor's WBCs?

Well i wonder if they are gobbling up the thymidine from the other patient might be in the media... one needs DNAases to break down DNA into thymidine.. i dont know why lymphocytes would need that since they arent in the business of lysis like neutrophils .. or staph aureus.

dTTPs are provided in the medium to measure proliferation.(please verify)

 

[JJtheMD]

i chose A cause i thought that immunosuprresants would make the graph more acceptable cause immosupresant decrease production and activity of immunlogical cells which would lower the value for the thymidine incorporation level which would then therefore decrease the chance of an autoreactive reaction... i think my thinking is wrong, or am i just not going deep enough.. this q confused me a little. meh idk hahaha

edit 2.. yup my thinking is wrong after reading the posts here lol.. ugh

 

[naiado]

I put B and got it wrong. Likely answer is A.

 

[Nambil]

Refer to:

http://books.google.com/books?id=EJ... incorporation kidney transplantation&f=false

you will found your answer....

 

[mayursn39]

This test is given in detail in Kaplan immunology..The answer is A..Thymidine incorporation value measures the proliferation of T cells in response to antigen which is MHC class II in this case.
As described above by some one this test requires an antigen ..For this we can use the recipients Tcells ..Now the test is as follows....
Recipients T Cells are irradiated to prevent it from proliferation.They will provide for the MHC antigens. When the donors Tcell are mixed with recipients irradiated T cells and if donors cell recognize it as foreign they will proliferate using up thymidine..Hence when the scores are low it means a better chance to match for tissue grafts..The test is done both ways..i.e donors cells are also irradiated and mixed with recipients Tcell to rule out mis match..

 

[dr.muhamad]

thymidine incorporation value??

what is thymidine incorporation value that is use in organ transplantation ??
any one knows??:scared::scared::scared:

 

[Glomerulus]

Hey Check out this link: http://www.usmle-forums.com/usmle-step-1-forum/1823-thymidine-incorporation-values.html

I think its a measurment about how reactive the t-lymphos of the host are going to be against the graft and a low value should be a good sign. Hope it helps!

 

[dr.muhamad]

Hey Check out this link: http://www.usmle-forums.com/usmle-step-1-forum/1823-thymidine-incorporation-values.html

I think its a measurment about how reactive the t-lymphos of the host are going to be against the graft and a low value should be a good sign. Hope it helps!

thank you

 

[Glomerulus]

No problemHappy-2Happy-2Happy-2 Was this in the NBME 7? Which NBME have u taken so far? Which one did u find the most difficult?