HLA-restricted and Antigen-specific CD8+ T Cell Responses by K562 Cells Expressing HLA-A*0201

Background: Identification of antigen-specific T cells has yielded valuable information on pathologic process and the disease state. Assays for quantification of inflammatory cytokines or lytic-granule molecules have been generally used to evaluate antigen specific T cell response, however their applicability have been hampered due to the limited source of autologous antigen-presenting target cells (APC). Methods: K562, a leukemic cell line deficient of human leukocyte antigen (HLA), was transfected with a gene encoding HLA-A*02 (K562/A*02) and its function as stimulator cells in inducing activation of HLA-matched T cells was evaluated by IFN-γ enzyme linked immunospot (ELISPOT) assay. Results: The stable transfectant K562/A*02 pulsed with HLAA*02 restricted peptide could specifically induce IFN-γ secretion by CD8+ T cells compared to no detectable secretion by CD4+ T cells. However, CD56+ NK cells secreted IFN-γ in both K562/A*02 with peptide and without peptide. The number of IFN-γ secreted CD8+ T cells was increased according to the ratio of T cells to K562 and peptide concentration. Formalin-fixed K562/A*02 showed similar antigen presenting function to live K562/A*02. Moreover, K562/A*02 could present antigenicpeptide to not only A*0201 restricted CD8+ T cells but also CD8+ T cells from A*0206 donor. Conclusion: These results suggest that K562/A*02 could be generally used as target having specificity and negligible background for measuring CD8+ T cell responses and selective use of K562 with responsder matched HLA molecules on its surface as APC may circumvent the limitation of providing HLA-matched autologous target cells. (Immune Network 2006;6(4):179-184)