Integrin α₃β₁ surface expression increases on human neutrophils during sepsis. (A) Integrin surface expression on neutrophils from SIRS patients (n = 9), sepsis patients (n = 15), and healthy donors (n = 7). Flow cytometry results expressed as a ratio of the integrin mean fluorescence intensity (MFI) to isotype control MFI of the same donor. *P < .05 (Wilcoxon rank-sum test). (B) Neutrophils isolated from healthy donors were stimulated with PMA (20 ng/mL), TNF-α (20 ng/mL), LPS (100 μg/mL), or fMLP (1 μM) for 1 or 3 hours. Fold changes in Itga3 gene expression, compared with unstimulated cells, were determined by reverse transcription polymerase chain reaction (upper panel), and surface expression of α₃β₁ was measured by flow cytometry (bottom panel). Data are expressed as mean ± SEM of 3 separate donors. *P < .05 (Mann-Whitney test). Integrin α₃β₁ is upregulated on mouse neutrophils in (C) CLP surgery and (D) endotoxemia models of sepsis. Cells isolated from bone marrow, peritoneal lavage, and peripheral blood of naive and septic mice at the indicated time points were gated for neutrophils using forward scatter/side scatter and Gr1^high expression. The results are expressed as % increases in MFI compared with naive controls (naive blood MFI was used to calculate the % change in peritoneal lavage [PL] expression). Data are expressed as mean ± SEM of 4 animals/time point.