Binding of HA-3^T and HA-3^M peptides to HLA-A*0101 and recognition by HA-3–specific T cells. (A) Binding of VTEPGTAQY (•) and VMEPGTAQY (○)to HLA-A*0101. HPLC-purified synthetic peptides were assayed for their ability to inhibit the binding of the iodinated peptide YTAVVPLVY to affinity-purified HLA-A*0101 molecules in a cell-free peptide binding assay (see “Patient, materials, and methods”). The HLA-A*0201–binding peptide IP30 (□) was used as negative control. (B) VTEPGTAQY (•) and VMEPGTAQY (○) were tested for their ability to reconstitute the epitope for the HA-3 CTL clone. Epitope reconstitution assay conditions are described in “Patient, materials, and methods.” An E/T ratio of 17:1 was used. Background CTL lysis in the absence of any peptide was 17%. Lysis of HoRe EBV-BLCL was 95%.