FIG. 3.

CD8⁺-T-cell lines recognize the HPV16 E7 and the coronavirus-derived peptide. T-cell lines (Table 4) were obtained by repetitive stimulation with the coronavirus-derived peptide TMLDIQPED as described and tested for recognition of each of the peptides listed in Table 1. Each peptide was pulsed in different concentrations on surrogate antigen-presenting T2 cells and tested for the capacity to induce GM-CSF or IFN-γ in responder T cells. Exclusively positive results are depicted. Note that also self peptides were recognized. T-cell clones or lines were derived from an apparently healthy HLA-A2⁺ individual. We could not establish T-cell clones from patients with CIN or cervical cancer. These T-cell lines recognized also naturally processed and HLA-A2 presented peptides on HPV16⁺ A2⁺ Caski cells or C1R A2⁺ cells expressing the coronavirus NS2 gene product, respectively (data not shown). Other HPV16 E7 variant peptides (listed in Table 1) did not yield detectable cytokine production. Symbols: red ovals and blue diamonds, viral antigens (coronavirus NS2 and HPV16 E7, respectively; squares, self peptides (YMLILHPET [yellow] and YMLSLHPED [green]).