T cells and DC carry reovirus for metastatic melanoma killing in vivo. C57Bl/6 mice (three per group) were seeded s.c. with 5 × 105 B16tk cells. After 10 days the mice were treated with PBS, 2 × 106 p.f.u. reovirus or 2 × 106 CTB-labeled Tcells, iDC or mDC loaded at MOI of 0 or 1. After 3 days the TDLN were explanted, dissociated and analysed by FACS; the percentage of adoptively transferred cells reaching the TDLN is shown—graphs show the mean values±s.e. of data from three mice (a). Delivery of reovirus to the TDLN was determined by plaque assay (b); graphs show the mean values±s.e. of data from three mice. (c) The presence of the HSVtk and Tyr-P (control) genes were determined by PCR; in addition, the dissociated TDLN were plated in puromycin-containing medium and the number of puromycin-resistant colonies counted. Individual results for each mouse are shown; the number of colonies after treatment with T(reo), iDC(reo), mDC(reo) and neat virus were all significantly lower than controls, P<0.01. In addition, for T(reo) and mDC(reo), P<0.05 compared to both iDC(reo) and neat virus.