[1] UNIV CALIF, SCH MED, DEPT MED, SECT IMMUNOL, SAN FRANCISCO, CA 94122 USA
[2] MEM SLOAN KETTERING CANC CTR, NEW YORK, NY 10021 USA
[3] ROCKEFELLER UNIV, NEW YORK, NY 10021 USA
[4] CHILDRENS HOSP, BOSTON, MA USA
[5] HARVARD UNIV, MED SCH, BOSTON, MA USA
[6] DEUTSCHE AKAD AUSTAUSCHDIENST, BONN, WEST GERMANY