I agree with everything above except that i am unaware of it affecting the levels of immunosuppressive medications. in addition, there is growing evidence that it may be increase liver fibrosis.
Just did a quick check on Google for "marijuana and liver transplant" and the following came up which might be pertinent to you.
From the Virginia Commonwealth University, Medical College of Virginia
Post liver Transplant Patient Handbook
"SMOKING AND ALCOHOL
You should not smoke cigarettes, cigars, pipes or marijuana!!!! Smoking narrows your
blood vessels which can be harmful to your liver and kidneys. Smoking also makes you
predisposed to lung infections. Marijuana causes your levels for your anti-rejection
medications, i.e. Neoral and Prograf to be very low, which could lead to rejection.
Marijuana also grows a fungus, known as Aspergillus, which can cause death in the
transplanted patient!!!!!"