Improved migration of activated T lymphocytes genetically modified to overexpress CCR4. (A) The expression of CCR4 in control (CTR) T cells and in T lymphocytes transduced with a retroviral vector encoding CCR4. Surface expression of CCR4 was evaluated by FACS analysis of CD3⁺, CD4⁺, and CD8⁺ T lymphocytes. represent the mean ± SD of control T cells; ■, mean ± SD of CCR4⁺ T cells. The data summarize the results of T-cell lines generated from 7 healthy donors. (B) A representative phenotypic analysis. (C) The migration of CTR () and CCR4⁺ (■) T cells toward TARC gradients, using a transwell migration assay. T-cell migration was evaluated using culture supernatants collected from 2 HL-derived cell lines (HDLM-2 and L428) that physiologically produce high amounts of TARC, and against the Karpas-299 cell line genetically modified to produce TARC (K/TARC). K/wt was used as a control. The panel indicates that migration toward TARC is significantly improved if T cells are genetically modified to overexpress CCR4. The data are the mean ± SD for T-cell lines generated from 7 healthy donors. (D) The improved migration of CCR4⁺ T cells (■) is TARC mediated as it is inhibited by addition of anti-TARC antibodies but not by the addition of an isotype control.