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My question is little bit related to this one Why does organ transplant work although it seems organ's motor neuron isn't connected to recipient's CNS but only little bit.

Problem

Suppose the case in which person A got his kidney transplanted (and person B is donor). Now both A and B have different DNAs and how come lung (organ) transplant works well for person A and how does person A's DNA going to "accept" the lung's DNAs and how is replication going to work across the foreign lung?

Question

Will person A's lung contain:

  1. Person A's DNA
  2. Person B's DNA
  3. DNA of both Person A and B (will convert to person A's after some-time having a certain half-life for it) or
  4. Forever contain both DNAs

Thanks in advance and kindly provide reference for your answer. Thanks

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  • $\begingroup$ The DNA plays no direct role in organ transplant acception (or rejection), since it is not recognized by the immune system. It is 99.99% identical anyways. Replication works in the normal way it always does. $\endgroup$ – Chris Jan 28 '16 at 12:01
  • $\begingroup$ Replication works in the normal way... So predict the DNA of the transplanted organ after lets say 1 day: Will it have all the DNA (DNA of all the cells I mean) converted into the person A's DNA? $\endgroup$ – Failed Scientist Jan 28 '16 at 12:14
  • $\begingroup$ Why should the DNA in the transplant be changed? And how should this happen? Technically you are chimeric after an transplantation. $\endgroup$ – Chris Jan 28 '16 at 12:17
  • $\begingroup$ Chimeric?? Any reference for this point kindly? $\endgroup$ – Failed Scientist Jan 28 '16 at 12:20
  • $\begingroup$ After a transplantation you contain the DNA of two different humans. $\endgroup$ – Chris Jan 28 '16 at 12:24
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4. Forever contain both DNAs

Yes, the donor kidney still has (and will remain to have) the donor's DNA. That is irrelevant to the acceptance and continued functioning of the organ, though.

The thing that could make an organ transplant fail is the recipient's immune system. If it detects the organ as "alien", it will attack it like any other foreign particle, and the body will reject the transplant.

To avoid this, two things are being done:

  • A donor is sought whose organs have similar protein markers to those of the recipient. (Those markers, and not the DNA, are what the immune system looks for when trying to tell friend and foe apart. DNA is inside the cell, the protein markers are on the outside.)

    Similar protein markers are usually found in people with similar DNA, which is why close relatives are tested for this kind of compatibility first.

  • The recipient recieves special drugs that partially suppress the immune system.

If the recipient's body does not reject the organ, it can continue to function normally despite its different DNA. If, for example, there is a genetic defect in there that will lead to some kidney-related issues at a later time, it will be the donor's defect. If there has been a defect in the recipients kidneys that would have led to issues later in his life, that defect would be gone with his kidney. Other cells in his body would still carry the same defect, but those cells are not kidney cells, and thus that particular issue will not manifest itself.

Replication of cells will follow the same pattern: Cells from the recipient will replicate the recipient's DNA, cells from the donor's organ will replicate the donor's DNA.

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  • $\begingroup$ In case this question was inspired by any novel / movie depiction of "his DNA was changed" and suddenly a person undergoing significant changes in appearance, capability, and / or personality (as in e.g. Star Trek or similar franchises), those are (largely) unscientific. Of course a donor organ could produce a very different mix of hormones, by- and waste products, with all the effects that could have -- but any "change" would be slow, gradual, and basically indistinguishable from naturally occurring changes in a person. With the exception that, without a donor, the recipient would be dead. $\endgroup$ – DevSolar Jan 28 '16 at 15:02
  • $\begingroup$ (ctd) Also, given that similarity in DNA / protein markers and healthiness of the organ is a basic requirement for organ transplantation, radically unbalanced organ functions are unlikely. $\endgroup$ – DevSolar Jan 28 '16 at 15:03
  • $\begingroup$ No this question came totally in my mind by chance (as these days all I think about is DNA). $\endgroup$ – Failed Scientist Jan 28 '16 at 15:28

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