What I would recommend is Synthrapol, which is a type of detergent. Synthrapol suspends loose dye particles in the water so they can be rinsed away. Be aware of two things. (1) Synthrapol requires hot water to be effective, and (2) you want to use a machine that uses a lot of water so that any additional dye bleeds are diluted. Domestic front-loaders do *not* use enough water for washing quilts that might bleed.
I always do my first wash of a quilt at the laundromat using their largest front-loading washing machine, Synthrapol, and hot water. This way any loose dye particles are suspended in the water and rinsed away, without a chance of settling into other fabrics. I have never had to wash a quilt more than once this way.
If you are dealing with a quilt which already has dye bleeds in it, Synthrapol will work to lift the dye bleeds out of the fabric but it may take more than one washing with Synthrapol to do the job completely. (Most dyes these days are not permanently set even with heat from a dryer, which is why Synthrapol still works even after dyes have bled into fabrics.)
Many dye bleeds are the result of over-saturation at the factory, with more dye in the original fabric than the fabric fibers can absorb. This excess dye, which is not permanently set, gets loose in the water and is picked up by other fabrics. Synthrapol helps prevent this "picking up" by other fabrics, and also works to get loose dye particles out of fabric.
Edit: Here's a link to a thread that shows the effectiveness of Synthrapol on dye bleeds:
http://www.quiltingboard.com/main-f1...x-t144836.html