FIG. 5.

(a) Illustration of the experimental procedure. Ten million DC^wt or DC^Dm-dNK activated with AddaVax Vaccine Adjuvant (InvivoGen, San Diego, CA, USA (1:1) were administered subcutaneously to the footpad of mice. Pyrrolo-dC was administered intravenously, 48 hours post-cell transplantation; and 2 hours postinjection, the PLNs were analyzed either by MRI or by FACS. (b) DC^wt and DC^Dm-dNK were incubated in vitro with 4 mM pyrrolo-dC. Histogram displays the relative fluorescence of control DC^{wt+Pyrrolo-dC} (red) and DC^{Dm-dNK+Pyrrolo-dC} (blue). Increased blue fluorescence corresponds to increased retention of pyrrolo-dC. No fluorescence was observed in the DC^wt without pyrrolo-dC (empty histograms). (c-e) Ten million DC^Dm-dNK stained with CFSE (CFSE⁺ DC^Dm-dNK) were processed and injected into mice as described in (a), and PLNs were harvested and analyzed by FACS. The myeloid cell population was gated based on forward-scatter and side-scatter measure of granularity and size, respectively, (c) and the pyrrolo-dC uptake of the CFSE⁺ DC^Dm-dNK cells (d and e; blue) was compared to the CFSE⁻ cells (APC-A channel is empty) (d and e; red). (f-h) Following the procedure described in (a), mice were imaged by MRI. CEST MRI map overlaid on anatomical MRI shows pyrrolo-dC accumulation in the PLN (arrow) of a mouse injected with DC^Dm-dNK (f; n = 5), but not with nontransduced DC^wt (g; n = 5). (h) Average MTR_asym values at 5.8 ppm plots of DC^wt and DC^Dm-dNK (mean ± standared error of the mean; n = 5 mice per group), Student t test, unpaired two-tailed, P value = 0.046.CEST, chemical exchange saturation transfer; CFSE, carboxyfluorescein succinimidyl ester; dC, dendritic cells; Dm-dNK, drosophila melanogaster 2′-deoxynucleoside kinase; FACS, fluorescence-activated cell sorting; PLN, popliteal lymph nodes; pyrrolo-dC, pyrrolo-2′-deoxycytidine; SSC, side scatter; wt, wild type.