[1] Wistar Inst Anat & Biol, Philadelphia, PA 19104 USA
[2] Fox Chase Canc Ctr, Div Med Sci, Philadelphia, PA 19111 USA
[3] Fox Chase Canc Ctr, Div Populat Sci, Philadelphia, PA 19111 USA
[4] Hosp Univ Penn, Dept Pathol & Lab Med, Philadelphia, PA 19104 USA
[5] Ctr Clin, Dept Transfus Med, Immunogenet Sect, NIH, Bethesda, MD 20892 USA