FIGURE 3.

Hierarchy of HCC patient responses to AFP peptides ex vivo. A, The hierarchy of response to AFP-derived peptides is shown for HCC patient A3. PBMC were thawed, and separated CD8 cells were plated directly in the IFN-γ ELISPOT with K562/A2.1 cells pulsed with individual peptides to determine the frequencies of peptide-specific T cells. T cells were detected to most of the peptides, with the highest frequency responses to AFP₁, AFP₂₁₈, and AFP₁₅₈. B, The hierarchy of response to AFP-derived peptides is shown for HCC patient B1. Cells were plated as above and the only responses were to epitopes AFP₁₃₇, AFP₁, AFP₃₀₆, and AFP₅₄₂. C, The median frequencies to each AFP peptide, for all six HCC patients (A3, A4, B1, B10, B11, B12) are shown; error bars indicate the first and fourth quartiles. The two-sided Wilcoxon test shows that, together, the six HCC patients have higher frequencies of T cells to the four immunodominant peptides, compared with the sum of the subdominant peptide frequencies (p = 0.023).