Enhancement of transmigration is not due to a secreted factor but is dependent upon cytoskeletal rearrangements with CD8⁺ cells.

Transmigration of CD34⁺ cells in the presence of untreated CD8⁺ cells (A), brefeldin A–treated CD8⁺ cells (B), or CD8⁺ cells pretreated with cytochalasin D (C) was measured as previously described. Solid lines link shared donor cell sources. The absolute numbers of cells that transmigrated are indicated in the tables beside the graphs. For all graphs, ⋄ represents experiment (expt) 1; ■, expt 2; ▴, expt 3; ×, expt 4; ●, expt 5; and ○, expt 6.