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Targeting CARVs using ex-vivo-expanded VSTs
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Figure 2. Specificity and enrichment of multi-res- piratory virus-targeted cells (multi-R-VST). (A) The specificity of virus-reactive T cells within the expanded T-cell lines following exposure to individ- ual stimulating antigens from each of the target viruses. Data are presented as mean± Standard Error of Mean (SEM) SFC/2x105 (n=12). (B) Fold enrichment of specificity [peripheral blood mononuclear cels (PBMC) vs. multi-R-VST; n=12]. (C) IFNγ production, as assessed by ICS from CD4 helper (top) and CD8 cytotoxic T cells (bottom) after viral stimulation in one representative donor (dot plots were gated on CD3+ cells). (D) Summary results for nine donors screened (mean±SEM).
post transplant for a subsequent pneumococcal pneumo- nia with concurrent detection (by PCR) of hMPV in spu- tum. His pneumonia was treated with antibiotics with subsequent resolution of disease and viral clearance, coin- cident with a marked expansion of hMPV-specific T cells (reactive against F, N, M2-1 and M), which increased from 4 SFC to a peak of 70 SFC and subsequent decline to base- line levels (Figure 5C). Again, the observed RSV-and hMPV-specific responses were independent of the overall increase in lymphocyte/CD4+ counts.
Online Supplementary Figure S7 shows the results of three additional HSCT recipients who developed CARV infections. Patient #3 is a 15-year old female with AML who received a haplo-identical transplant with reduced intensity conditioning, and developed an RSV-induced URTI and LRTI while on tacrolimus five weeks post transplant. The patient was administered ribavirin and the infection resolved within four weeks. We monitored RSV-reactive T cells over time and viral clearance coincid- ed with a striking increase in the frequency of RSV-specif- ic T cells (from 0 to 506 SFC/5x105 PBMC) (Online
Supplementary Figure S7A). Similarly, Patient #4, a 10-year old male patient with ALL who received a MUD trans- plant with myeloablative conditioning, developed a PIV3- related URTI and LRTI one month after HSCT while on tacrolimus. His infection symptomatically resolved with- in five weeks, coincident with the administration of rib- avirin. To investigate whether endogenous immunity also played a role in viral clearance, we monitored PIV3-reac- tive T-cell numbers over time. Viral clearance was accom- panied by an increase in the circulating frequency of T cells specific for the PIV-3 antigens M, HN, N and F (peak 38 SFC/5x105 PBMC) with subsequent decline (Online Supplementary Figure S7B). Finally, we show Patient #5, a 3-year old male with chronic granulomatous disease who received a MRD transplant with myeloablative condition- ing and developed a severe PIV-3-related URTI four months post HSCT while on cyclosporine. The patient received ribavirin but (at last timepoint assessed) contin- ued to exhibit disease symptoms and failed to demon- strate PIV-3-specific T cells (Online Supplementary Figure S7C). Taken together, these data suggest the in vivo rele-
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