Figure 1

Antigen-specific CD8 T cell response to peptides <8mer. (a) PBMCs stimulated with SSCSSCPLSK as well as its C-terminal and N-terminal short peptides were assayed by ELISpot. Data from a representative HLA-A*11:01 homozygous individual is shown. TYGPVFMCL peptide (HLA-A*24 restricted) served as the control. (b) Counts of IFN-γ secreting spots from HLA-A*11:01 individuals (n = 8) represented as dot plot. Positive response defined as > 2 times negative control value and > 15 SFU/ 10⁶ PBMCs. Length of peptide affects T cell response (Cochran’s Q test, p = 0.00495), statistically significant pairwise comparisons are indicated (McNemar post-test; **p < 0.01; *p < 0.05). (c) FACS plots from a representative HLA-A*11:01 homozygous donor’s 14-day PBMC culture show detection of T cells by A*11:01/SSCSSCPLSK tetramer following stimulation with SSCSSCPLSK, SCSSCPLSK, CSSCPLSK or SSCPLSK. PBMC cultures stimulated with irrelevant peptide control, HLA-A*24-restricted EBV peptide (TYGPVFMCL), were similarly stained with A*11:01/SSCSSCPLSK tetramer to serve as a negative control. (d) Line graph depicting A*11:01/SSCSSCPLSK tetramer-positive CD8⁺ cell percentages in eight A*11:01 positive individuals. Positive response defined as > 2 times control peptide value and more than 1% of the CD8⁺ cells. Length of peptide affects percentage of double-positive T cells (Cochran’s Q test, p < 0.001), statistically significant pairwise comparison with negative control are indicated (McNemar post-test). (e) FACS plots from a representative HLA-A*11:01 homozygous donor’s 14-day PBMC culture show CD8 and A*11:01-SSCSSCPLSK tetramer double-positive cells expressed intracellular IFN-γ and surface CD107a after re-stimulation with SSCSSCPLSK, SCSSCPLSK, CSSCPLSK or SSCPLSK.