Changes in EC stiffness on neutrophil adherence.

After TNF-α was washed off, the stiffness of 24-hour TNF-α–treated ECs (A) or untreated ECs (B) was measured by magnetic twisting cytometry using ferromagnetic beads bound to β₁ integrin as described in “Materials and methods.” After the measurement of baseline stiffness, either purified neutrophil (neutrophil to EC ratio, 1:1), buffer, or neutrophil supernatant was added to the well, and EC stiffness was measured 2, 6, 10, and 15 minutes later. Data are expressed as mean ± SEM (n = 4). *P < .05 when compared to the baseline stiffness. ●, addition of neutrophils; ▪, addition of buffer; ■, addition of neutrophil supernatant.