FIG. 7.

CD4⁺ T cells migrate across B. burgdorferi-stimulated HUVEC in an MCP-1-dependent manner. CD4⁺ T cells were incubated for 2 h with HUVEC-amnion cultures that had been pretreated with either control medium (Unstim), 5 U of IL-1 per ml, or B. burgdorferi at a ratio of 10 Bb/EC (A). CD4⁺ T cells were incubated for 2 h with HUVEC-amnion cultures that had been pretreated with either control medium (Unstim) or B. burgdorferi at a ratio of 10 Bb/EC in the presence of no MAb, an isotype-matched control MAb (MOPC-21), or 20 μg of neutralizing anti-MCP-1 MAb per ml (B). Transendothelial migration was assessed as described in Materials and Methods. The total height of each bar represents the number of T cells associated with each culture as a percentage of the total number added. The lower portion of each bar represents the percentage that migrated beneath the endothelium; the upper portion represents the percentage adherent to the apical surface. Bars represent the means ± SD of four to five replicate samples.