Background and aims: Aspergillus fumigatus infections are the leading cause of invasive fungal infection-related deaths in stem cell transplant patients, and may be amenable to correction with adoptive immunotherapy providing T lymphocytes specific for A. fumigatus. However, a clinically usable source of antigen and a reliable procedure for the generation of large numbers of Aspergillus-specific T lymphocytes to clinical-grade standards is not available.
Methods: An environmental strain of A. fumigatus (WMAfES) was isolated and cultured using materials and reagents suitable for clinical manufacture. Water-soluble lysate from germinated conidia of WMAfES was used as the antigen source. Peripheral blood mononuclear cells were stimulated with antigen-pulsed autologous dendritic cells on days 0 and 7. Cells were expanded with a cocktail of interleukin (IL)-2, IL-7 and IL-15 from days 7 to 21.
Results: We obtained a mean 32.8-fold increase in cell numbers over 21 days of culture (n = 8). Resultant cultures were predominantly effector and central memory CD4(+) T cells, which produced T-helper (h)1 and Th17 cytokines when restimulated with A. fumigatus antigen derived from environmental or clinically isolated A. fumigatus. Cultured cells exhibited a high level of specific expansion and chemokine production when restimulated. Moreover, cultured cells cross-reacted with antigens from other fungi, including Penicillium, Candida albicans and other non-fumigatus Aspergillus species.
Conclusions: We describe a simple, robust, reproducible and clinically applicable procedure using a clinically appropriate antigen preparation for the expansion of polyfunctional A. fumigatus-specific T cells from normal donors of varying HLA types.