S. Stevanovi6• H.-G. Rammensee (~) Abteilung Tumorvirus-Immunologie (0620), Deutsches Krebsforschungszentmm, Im Neuenheimer Feld 242, D-69120 Heidelberg, Germany gene used for transfection had been cloned from a Japanese individual and was confirmed by sequencing to be B'I501 (M. Takiguchi and co-workers, unpublished results). Transfectants were expanded in about 30 to 50 1 of roller bottle cultures. Cell pellets of 20 to 50 ml were detergent lysed, and the HLA molecules precipitated, using HLA-A-, B-, C-specific W6/32 antibodies (Barnstable et al. 1978), as described previously (Falk et al. 1991). Peptides were dissociated from HLA molecules by treatment with 0.1% TFA and separated on a 2.1 xl00 mm reversed phase C2/C18 HPLC column (Pharmacia, Freiburg, Germany); using the SMART system (Pharmacia). Material eluting in dis-