Chemotaxis of human and murine T lymphocytes to conditioned media of genetically modified DCs. (a) CEM cells. Human T lymphocyte CEM cells placed in the upper chamber of a transwell chamber were assayed for chemotaxis in response to serial dilution of supernatant from DCs transduced with AdMDC, AdNull, or PBS alone (naive control) in the lower chamber. (b) EL4 cells. The study was similar to that in a, but the murine T lymphocyte EL4 cell line was used. (c) Suppression of AdMDC-mediated chemotaxis. CEM and EL4 cells were assayed for chemotaxis in response to 1:2 dilution of supernatant from AdMDC-modified DCs. Where indicated, anti–MDC neutralizing Ab or mouse IgG control Ab was added to the supernatant in the lower chambers at 10 μg/ml at the initiation of assay or cells were placed to the upper chamber in the presence of recombinant (r) MDC or TARC at 100 ng/ml. For all parts, the number of cells migrating to the lower chamber at 37°C for 4 hours was counted by FACS analysis. Migration index was calculated as the number of cells migrating to the conditioned media over the number of cells migrating to control medium. Results represent the mean ± SE (n = 3 per data point).