T-cell response against the HOM-TES-14/SCP1–derived peptides. (A) Autologous PBMCs (5 × 104/well) were used as APCs to stimulate bulk T cells of 7 patients. T cells (2.5 × 104 CD4⁺ T cells/well) from 1 of 7 of these patients showed a significant response against peptide p635-349 after stimulation for 21 days with PBMCs loaded with the first pool of 7 SCP1-derived peptides (P < .001). The p635-649–specific response was of a magnitude similar to that of T cells that had been prestimulated with a pool of 7 peptides derived from the pp65 antigen of the human CMV under the same conditions. (B) No significant response was observed after stimulation with 7 additional HOM-MEL-14/SCP1–derived peptides constituting the second pool. In the absence of effector cells, the autologous APCs did not secrete IFN-γ.