Asacol never worked for me either. I'm not convinced it didn't work for you because "your immune system was too strong"; rather, I think there are probably a myriad of subclasses to Crohn's and ulcerative colitis that have yet to be identified. In fact, I remember reading an article Jan posted that discussed how scientists have so far discovered at least 99 different loci in the DNA which can trigger UC. This makes sense, and could be an explanation for why some treatments work well for some people but have no effect on others. It's why I always tell people that most things are worth a try, even if they didn't work for me. Hopefully in the not-so-distant future, they'll have more targeted therapies for people based on which of their genes have mutated.