Multispecific Aspergillus T Cells Selected by CD137 or CD154 Induce Protective Immune Responses Against the Most Relevant Mold Infections

Background. Aspergillus and Mucorales species cause severe infections in patients after hematopoietic stem cell transplantation (HSCT). Induction of antifungal CD4(+) T-helper type 1 (Th1) immunity is an appealing strategy to combat these infections. Immunotherapeutic approaches are so far limited because of a lack of antigens inducing protective T cells, their elaborate production, and the need of targeting a broad spectrum of pathogenic fungi. Methods. We examined the response to different Aspergillus fumigatus proteins in healthy individuals and patients after HSCT and compared rapid selection protocols for fungus-specific T cells based on CD137 or CD154 expression. Results. The A. fumigatus proteins Crf1, Gel1, and Pmp20 induced strong Th1 responses in healthy individuals. T cells specific for these antigens expanded in patients with active invasive aspergillosis, indicating their contribution to infection control. Th1 cells specific for the 3 proteins can be selected with similar specificity within 24 hours, based on CD137 or CD154 expression. These cells recognize naturally processed A. fumigatus and the multispecific T-cell lines, directed against all 3 proteins, especially those selected by CD154, additionally cross-react to different Aspergillus and Mucorales species. Conclusions. These findings may form the basis for adoptive T-cell transfer for prophylaxis or treatment in patients with these devastating infections.