They drove from New York, New Hampshire and Vermont, and from cities and towns all over Massachusetts. They came after soccer games or before football or on their way to the supermarket. Some came directly, on a glorious September weekend, when they could have been anywhere else - visiting friends, golfing, shopping, watching the Red Sox. Dozens came, alone and in pairs, young and old, male and female, to the gymnasium at Brockton High School to fill out a form and wait in a line and have their arm pricked and blood drawn, when they didn't have to, when no one forced them.