Yes. I think the immunosuppressive side-effects of AZA are fairly well documented in the medical literature. Wikipedia has a fairly good entry on it, but a quick google search will bring up some entries.
I was fairly well controlled on mesalamines, so I discontinued it because it simply was not worth taking. It never suited my system and I felt dead while on it. However, I understand it is keeping some folks in remission. For some, the long term risks are worth it if it is keeping their colitis in control, so it's a tough decision. I personally would not opt to be on it long term due to the fact that it was recently classified as a carcinogen.
Best.
Post Edited (Guardian7) : 1/8/2015 9:17:10 AM (GMT-7)