Human airway epithelial cells present antigen to influenza virus-specific CD8+ CTL inefficiently after incubation with viral protein together with ISCOMATRIX®

In the present paper, an in vitro model was established in which the interaction between influenza virus-specific CD8+ T cells and human airway epithelial cells can be studied. To this end, the human lung epithelial cell line A549 was transduced with the HLA-A*0201 gene. This MHC class I allele is involved in the presentation of the immunodominant M1_58-66 cytotoxic T lymphocyte (CTL) epitope of the influenza A virus matrix protein. The A549-HLA-A2 cells and a CD8+ T cell clone specific for the M1 _58-66 epitope were used to evaluate ISCOMATRIX^® (IMX), which is considered a potential mucosal adjuvant for influenza vaccines, for its capacity to activate virus-specific CTL after incubation with epithelial cells. It was found that virus infected epithelial cells activated virus-specific CTL efficiently. However, incubation of epithelial cells with ISCOMATRIX^® and recombinant M1 protein activated CD8+ T cells inefficiently, unlike the incubation of C1R cells expressing a HLA-A2 trans gene or HLA-A2+ B-lymphoblastoid cells with these reagents. It was concluded that this lack of antigen presentation by epithelial cells indicate that these cells are not subject to killing by virus-specific CTL upon instillation with ISCOMATRIX^®-based vaccines, which may be a favorable property of mucosal vaccines.