Circulating peptide-specific T cells directed to tumor-specific IgH-encoded epitopes in a vaccinated patient. (A) PB samples were obtained from patient no. 14 at the indicated time points before (pre) and after (post) vaccination. (B) Synthetic peptides (indicated as peptides nos. 1, 2, and 3) corresponding to CDR1, FR1, and CDR3 sequences of the tumor-specific IgH sequence from patient no. 14 were used to assess cytokine release by circulating T cells by ELISPOT. Fluorescence index (FI) as evaluated by the HLA-A2 stabilization assay after staining of T2 cells with mAb CR11.351 (a) or BB7.2 (b). (C) Frequencies of IL-4– or IFN-γ–producing T cells against peptides nos. 1, 2, and 3, as evaluated by ELISPOT in blood samples taken before and after vaccination from patient no. 14. The HLA-A*0201–binding HIV peptide ILKEPVHGV was used as negative control in both the IL-4 and IFN-γ assays. Response to this peptide was fewer than 10 spots/106 cells in all blood samples analyzed. * indicates frequency of cytokine-releasing T cells, in the indicated blood samples, was significantly higher compared with prevaccination values (Mann-Whitney test, P < .05). Error bars indicate standard deviation of the mean.
