FIG. 1.

Stimulation of HUVEC with B. burgdorferi for 8 to 24 h results in maximal migration of T lymphocytes. Unfractionated T lymphocytes (10⁶ per culture) were incubated for 2 h with HUVEC-amnion cultures that had been treated with either a sham preparation of spirochetes or B. burgdorferi (Bb) at 10 bacteria/endothelial cell for 4, 8, or 24 h. The total height of each bar represents the number of T lymphocytes associated with each culture, expressed as a percentage of the total number of cells that was initially added. The lower portion of each bar depicts the percentage of cells that migrated beneath the endothelium. The upper portion of each bar denotes the percentage of T lymphocytes that were adherent to the apical surface of the endothelium. Bars represent the means ± standard deviations (error bars) of three to four replicate samples. Asterisks denote levels of migration across B. burgdorferi-stimulated endothelium that are significantly different from those across sham-treated controls: ∗, P < 0.01; ∗∗, P < 0.001.