Fig. 6

Enhanced in vivo cytolytic activity against target cells expressing CD47, the ligand for signal-regulatory protein alpha. Naive and mice chronically infected with Friend virus (FV) were adoptively transferred with differentially fluorophore-labeled target cells as outlined in a and in Methods. Briefly, wild-type C57/BL6 splenocytes were differentially labeled with two concentrations of carboxyfluorescein succinimidyl ester and CD47^−/− splenocytes were differentially labeled with two concentrations of CellTrace^TM-violet. The brighter of each subset was peptide-loaded with 25 μM FV-D^bGagL peptide, while the lower intensity subset was sham-loaded in dimethyl sulfoxide media. a The gating strategy identifying the target cell populations and representative dot plots showing target cell populations (b) before injection and retrieved from (c) naive and (d) chronic recipients 6 h post-transfer. The percentages given are the means for each cell subset combining data from two independent experiments. e, f The percentage of killing comparing C57/BL6 WT and CD47^−/− target cells as described in Methods. The data points showing the killing of each type of target cell within the same recipient mouse were connected with a line and the differences were statistically significant as indicated by two-way paired t tests. Data from the two independent experiments include a total of 20 mice. Virus-specific killing is defined as the percentage of killing of each population of FV peptide-pulsed cells calculated as follows: 100 – ([% peptide pulsed in infected/% un-pulsed in infected)/(% peptide pulsed in uninfected/% unpulsed in uninfected)] × 100). The flow cytometric gating strategy is shown in supplementary Fig. 6n–p