Fig. 7

Chemotactic response of U937 cells to Dyn A. a, schematic representation of the experimental format. U937 cells (5x10⁴) were placed in the center of the coverslip between two agar gels, one containing Dyn A and control gel without Dyn A. After 2 h at 37 °C, a series of photographs was taken in the direction of migration at 1-mm intervals to count the number of migrating cells. b , representative images after 2 h of migration show the cells within the starting point (marked with a cross; right panels) and at the border of the Dyn A-containing agar drop (left panels). Some cells were incubated with mAb 44a (20 μg/ml) or naloxone (10 μM) for 30 min before the initiation of chemotaxis assays. Two bottom panels show the experimental condition with no Dyn A gradient. c, quantification of U937 cells migrated from the initial point after 2 h based on the results shown in A (right panel). Migration of control untreated U937 cells that completely migrated from the initial point of cell placement was assigned a value of 100 %. In contrast, there was no cell migration without a Dyn A gradient (0 %). Migration of cells preincubated with mAb 44a and naloxone was blocked by ~80 % and ~20 %, respectively. A representative experiment is shown. d, distribution of U937 cells between two gels: Dyn A-containing (on the left) and without Dyn A (on the right). “0” on abscissa corresponds to the initial point where cells were loaded and the numbers show the distance that cells migrated in both directions from the starting point. All cells in each of 10 consecutive fields towards the Dyn A-containing and empty gels were counted and plotted as a distance from the starting point