Fig. 7

Patients’ resistance to the Trojan horse is associated with critical HLA mismatches and the rapid induction of anti-stem cell cytotoxic and interferon responses. a The SIBD01 and SIBD02 blood donors (MSC recipients) demonstrate broad resistance and permissivity to 4 allogeneic ADSC lines, respectively. Plaque assays were performed on 48 h cocultures of 250,000 PBMCs from the two blood donors with 40,000 or 5000 ADSCs infected with 5000 pfu of WT1 VV. The 4 allogeneic ADSC amplified vaccinia virus only in the presence of PBMC from the permissive SIBD02 blood donor. Bars represent duplicate measurements ± SD. b Precise HLA typing using NSG technology reveals loci potentially associated with permissiveness versus resistance to the four allogeneic ADSC lines, but alone cannot predict it (PAR permittivity associated region). To facilitate comparison the HLA alleles of the permissive and resistant blood donor are shown with red and blue font, respectively. c Correlative flow cytometry analysis of gated live NK and T cells from the PBMC/ADSC/WT1 co-cultures as in a showing that all 4 of the allogeneic stem cell lines tested induce much stronger CD107α and IFNγ responses in the NK and T cells from the resistant (black) but not permissive (red) blood donor, even in the absence of the virus. The figure shows the average percentages of CD107α or IFNγ single positive lymphocytes of each cell type based on triplicate wells and normalized to respective background (Untreated PBMC CTRL). Note that in the permissive blood donor the four allogeneic stem cells suppressed spontaneous NK cell-mediated IFNγ responses below background (Untreated PBMC CTRL). d CD3+ NKp46 + NKT-like cells are present at higher frequency in the resistant SIBD01 but not the permissive SIBD02 blood donor and expand in response to the allogeneic stem cell lines alone, which is increased even further in the presence of virus infection. Bars represent triplicate measurements ± SD. Asterisk was used to mark statistical significance (Student T-test, p < 0.05) relative to the respective (−) ADSC CTRL group or between groups as indicated