Another unique mystery about the liver.

[Richard-Allen]

Every now and again I like to post some interesting facts about this most wonderous organ. Those of you who have completed the two online liver courses, "Liver Disease: Looking after Your Liver" and "Liver Transplant: the Ins and Outs" will know of Dr Patricia Laylor.

Back in 2017 Dr Laylor and I exchanged a number of emails, she very kindly explained and answered a few questions I had concerning organ rejection and DNA.

For those who may be interested, here is my question, followed by Patricia's reply:

My Question:

I understand the liver structure bit and the various cells that make up the liver. My problem concerns the Deoxyribonucleic Acid (DNA). I don’t know which of these liver cells carries the DNA, but I can understand how when a liver is transplanted from the donor into the new host, the body’s immune system will see this as a threat and attack the new liver as the DNA in the nucleus of a liver cell is different. I also understand that the DNA in the donor's liver never changes. This is my problem… If a transplant is carried out as a split-liver transplant, then how is the liver regrown with the donor’s DNA if it’s no longer in the donor’s body?

The same could be said about any damage caused to a transplanted liver, is the liver still able to repair its self using the donor's DNA?

I hope you can understand what I’m trying to say ?

I did happen to ask Professor Gideon Hirschfield this question when I attended one of the clinics. But I’m afraid to say his explanation went straight over my head.

The Reply :

The DNA is like the computer program for the cells. Its found in every cell inside the nucleus. It is essentially the instructions for machinery within the cell to make all the proteins and structures the cell needs to survive.

Some of these proteins are found on the membrane or ‘skin' of the cell and it is often these that are used by the immune system to recognise if a cell belongs to the host or is foreign and should be attacked and cleared by the immune system.

So it is the proteins that are seen as foreign rather than the DNA itself.

Under most circumstances, a foreign cell (for example part of a skin graft or transplanted kidney) would be detected and killed by the immune system when it ‘sees’ the foreign antigens. However, the liver is a bit special in this regard. Because it is involved indigestion, it is exposed to loads of foreign protein that comes in with the blood as products of digestion from the intestines. If the immune cells in the liver were to react to all these you would never get any nutrients and the immune system in the liver would get out of control.

So the blood cells inside the liver include special immune cells that induce ‘tolerance’ or if you like ignore some foreign proteins. Also when you have a transplant some of the cells that initiate and regulate the processes of immune responses are delivered from your recipient bone marrow into the new organ, and some come from the new donor organ itself when it is transplanted. Thus the liver has ways to be less immune reactive and can be tolerated better than other organ grafts.

I hope some of you like me find this to be totally interesting stuff. Patricia did also include a number of links to other sites for further information, these are:

1: hindawi.com/journals/jir/20...

2: youtu.be/zwibgNGe4aY(Not working as expected?)

3: youtu.be/gG7uCskUOrA(Not working as expected?)

Best Wishers to one and all.

Richard

[AMDA26]

So does this mean a liver is less likely to reject than another organ for example? I am aware that a liver can regenerate but how is it that a liver can regenerate but not other organs. I find that fascinating

[Richard-Allen in reply to AMDA26]

I guess Amda, that this is one of those remarkable things that make the liver so unique. It’s one of those mysteries of life. The liver is part of our bodies immune system as it processes all those toxic substances. The liver passes around 2000 litres of blood and filters it 350 times per day. Because of this, the rest of the body's immune system cuts it some slack and doesn’t see the liver as a threat and allows it to do its own thing.

So there is less chance of rejection than there is with other transplanted organs. That’s not to say the immune system doesn’t sometimes go wrong. Organ rejection will always carry risks of rejection.

[AMDA26 in reply to Richard-Allen]

That’s interesting. I wonder if all these findings will help to develop treatment for liver disease patients/ transplant recipients. It seems that the liver is very complex.

[AyrshireK]

This probably explains why a liver donor doesn't have to be a tissue type match to a recipient just a blood group match unlike kidneys, hearts etc. which have to be tissue matched.

[Richard-Allen in reply to AyrshireK]

I must admit Katie, I like posting up these sort of posts up. They tend to get a good response and I think those with liver disease have a thirst for a great understanding of their condition. The liver remains a secretive organ and bit by bit it’s slowly giving up its secrets.

[Braveheart65 in reply to Richard-Allen]

It begs the question then, why can’t we tissue type the recipient and the donor organ not for compatibility but to extract DNA such that synthetic DNA can be prepared which is given to recipient such that rejection becomes unlikely and lifelong anti rejection drugs obsolete?

First time I’ve come across your posts, thankyou for keeping minds active.

[Danubian]

I know this is not at all scientific, not proven but of interest to me nevertheless. While having acupuncture done, I looked at the charts on the wall linking organ problems to psychological states - and with the liver it was Zorn (anger, wrath, rage). And funnily enough, whilst visiting my 92 year old aunt, she was talking about old family members of hers who past away. She told me of an uncle of hers - and she told me that he died of liver failure because he was very, very "zornig". Is this all humbug?

[CocoChannel in reply to Danubian]

Even I don’t know what zornig means, but i did know where to find DNA.

bbc.co.uk/bitesize/topics/z...

[witchiegirl]

Fascinating

[Hidden]

Hi

Very interesting. Thank you for sharing this ,much appreciated.

Take care and stay safe Lynne

[Hidden]

Thanks for such a thought provoking post.