Generation of Aspergillus-specific T lymphocytes with cytotoxic activity

Dendritic cells (DC) are highly specialized antigen presenting cells with the unique capacity to initiate and direct immune responses. The superior ability of DC to present antigens to T cells has led to the development of DC-based strategies for the purpose of enhancing the immune response against tumors and infectious agents. In this study Aspergillus (Asp)-pulsed DC were used to generate Asp-specific cytotoxic T-lymphocytes (CTL). Two different Asp-antigen preparations were used here. Asp-specific CTL were generated by four stimulations with autologous, mature, monocyte (Mo)-derived DC that are pulsed with either Aspergillus crude extract (CE) or culture filtrate (CF) antigens. The cytolytic activity of the generated CTL was assessed one week after the 4th stimulation by chromium release assay. No significant difference (p > 0.05) was found between the proliferative responses induced by either CF or CE Asp-pulsed DC. Both types of Asp-pulsed mature DC were capable of priming Asp-specific CTL responses. Analysis of the Asp-CTL effectors revealed that they are mixed of CD3+/CD4+ and CD3+/CD8+ populations and that they secrete IFN-gamma in response to Asp-pulsed mature DC and specifically kill autologous DC pulsed with the same Aspantigen. The killing was higher in bulk-cultures generated using Asp-CF pulsed DC. The percentage of CD3+/CD8+ cytotoxic T cells was significantly increased (p < 0.001) in Asp-CF bulk-culture when compared with Asp-CE bulk-culture (31.55 +/- 1.96% versus 9.70 +/- 1.84%, respectively). In conclusion, Asp-specific T cell lines with cytotoxic activity can be generated from healthy donors. These cells may be used as prophylaxis in high-risk immunocompromised patients.