Abstract: Objective To study the roles of phenotype switch of HPV16 antigen-specific CD8⁺ cytotoxic T cells (CTLs) in peripheral blood as well as the cellular immune response of human T lymphocytes to viral peptides in the pathogenesis of condyloma acuminatum.Methods HPV16E7_11-20 (HLA-A^*0201/YMLDLQPETT) antigen-specific CTLs were stained with fluorescent-labeled recombinant MHC class I-peptide pentamer complex,and co-stained with CD69 (activated CTL) and CD45RO (memory CTL) surface markers,in peripheral blood from 10 patients with condyloma acuminatum and 15 normal controls.The CTLs were quantitated by flow cytometric analysis.Meanwhile,peripheral blood mononuclear cells of 13 healthy donors were incubated for 7 days with HPV16E7_11-20 peptide,recombinant human interleukin 7 and interleukin 2 to yield antigen-specific CD8⁺ CTLs and their other surface markers.An irrelevant peptide,HBVcore_18-27 (FLPSDFFPSV),was used as an isotype control.Results The percentages of peripheral blood HPV16E7 antigen-specific CD8⁺CTLs,activated CTLs and memory CTLs of total CD8⁺ T cells were increased significantly in patients with condyloma acuminatum (0.76%±0.43%,0.36%±0.20%,and 0.33%±0.15%,respectively) than those in normal controls (0.24%±0.07%,0.17%±0.05% and 0.15%±0.06%,respectively) (P<0.01,P<0.05,and P<0.01,respectively).For T cells in vitro stimulated with viral peptide for 7 days,the percentages of peptide-specific CD8⁺ CTLs,activated CTLs and memory CTLs were significantly higher (0.75%±0.16%,0.35%±0.15% and 0.33%±0.18%,respectively) in comparison with those in non-stimulated group (0.24%±0.06%,0.16%±0.03% and 0.13%±0.04%,respectively) (P<0.001,P<0.01 and P<0.01,respectively).Conclusions These results,in vivo and in vitro,demonstrate that the proliferation of CD8⁺ T cell clones induced by HPV infection could generate antigen-specific CD8⁺ CTLs,causing a highly efficient and specific killing of viral-infected target cells directly,which may play an important role in antiviral T cell-mediated immune response.

Key words: Condylomata acurninata, Papillomavirus,human, T-lymphocytes,cytotoxic