Synthrapol, but be sure to use it in a machine with ***lots*** of hot water. Domestic front loaders don't use enough water to allow Synthrapol to work its magic. If you use a laundromat front loader, depending on the size of the quilt, go up at least one size over what you normally would use. One thing about front loaders is that they are a lot easier on the quilt (and clothing) than top-loading agitators.
Also, be sure to take the quilt out right away to dry. You do not want damp fabric sitting next to damp fabric; dye can transfer that way too. Keep the quilt moving while it is wet.