HLA-restriction and the target cell specificity of leukemia reactive T-cell clones 2.4.1 and 2.4.8. (A) MoAbs against HLA-DR (B.8.11.2), -DP( B7/21), -DQ(SPV.L3) and HLA class I (W6/32) were added in the proliferation assays at a final dilution of 1:200. The results are expressed as % inhibition of the proliferative response in the absence of antibodies. (B) The proliferative response of HLA-DP–restricted T-cell clones, 2.4.1 and 2.4.8, against leukemic cells and nonleukemic cells. The data represent the summary of eight independent experiments. HLA-DPB1*1301–specific and HLA-DRB1*1302–specific T-cell clones were used as control. Besides patients’ EBV-LCL, autologous BM, and PBMC, two HLA-DP and DR-matched PBMC from unrelated donors were tested as stimulator cells.