One thing that Cantorna and others found in their experiments with Vitamin D and animal models of autoimmune disease, was that the animals did better with a combination of Vitamin D/calcium than with just Vitamin D alone - particularly the female subjects. Of course, these were animal experiments, so take it for what it's worth.
I'm sure JL will agree, if you're supplementing with high doses of Vitamin D, you will probably want to get your blood checked at some point, to see what the level is. At the time of my diagnosis, I was around 21 ng/ml. I started supplementing, and though I wasn't real consistent, the last few months I was doing about 5000 IU's per day (at no point was I ever more than this). In January, after about a year and a half, I got my level tested again, and it was in the high 70's (ng/ml). This was such a big swing, I'm going to get it checked again, just to verify the level. Of course, that 5000 IU/day didn't include natural sources (I have been eating a lot of fish).