Engineering in rejection of transplants

http://aaqg-arunarya.blogspot.in/2017/07/engineering-in-rejection-of-transplants.html
http://www.sciencealert.com/this-protein-could-explain-why-our-bodies-reject-transplanted-organs?perpetual=yes&limitstart=1

There are plenty of cadavers, and people willing to part with redundant safety organs, to provide many transplants if the problem of rejection can be safely overcome. Standard technique so far is to address the problems of rejection by depressing the immune system of the receiver enough to allow the transplant to merge with patient system enough that it is no longer considered foreign.

Buried in this narrative is science. The body has developed markers to differentiate friend protein from foe. Depression of the immune system opens the body to all opportunistic infections and cancers. That is solely because of friend/foe identification at protein level.  A type of receptor on bone marrow cells called signal regulatory protein alpha (SIRPα) has been identified by scientists from the University of Pittsburgh as the body's watchdog responsible for dispatching the lymphocytes that target and destroy foreign cells. The mechanisms behind the white blood cell assault are fairly well understood – molecules on the outside of the cells belonging to what's called the major histocompatibility complex (MHC) identify them as different. A type of white blood cell called a T lymphocyte has receptors on its surface capable of recognizing unknown MHC proteins and responds by attempting to break up the foreign material they're attached to.

Lymphocytes aren't born knowing what's foreign and what's not; they need to be taught. Which is the job of another part of the immune system called a dendritic cell. Dendritic cells chew up foreign proteins and weave them into their own MHC before displaying them on their surface like a microscopic 'wanted' poster. They then migrate into the body's lymph nodes where they interact with the gun-slinging T lymphocytes.

A better match between the donor's and recipient's SIRPα genes could help reduce the risk of the immune response being sparked in the first place. Like blood typing, MSC matching. Not yet, since still 1-10 or 1-20 chances’ of rejection, so have to immune-suppress all, to be on safe side. Will I take these odds? What are the odds of infection/cancer if immunosuppressed? When that happens, engineering starts!