Integrin affinity changes in aged neutrophils. Using multichannel flow cytometry, binding of the β2 integrin ligand ICAM-1/CD54 to aged and nonaged neutrophils isolated from the peripheral blood of WT mice was analyzed as detailed in “Methods.” (A) Representative flow cytometry histogram and quantitative data for neutrophils isolated from the peripheral blood of WT mice undergoing exposure to PBS or LPS, as well as to the TLR-4 inhibitor TAK-242 or the MAPK inhibitor compounds FR180204 (ERK 1/2 MAPK), SB203580 (p38 MAPK), or SP600125 (JNK 1/2/3 MAPK). Mean ± SEM for n = 4-6; *P < .05 vs PBS; ^§P < .05 vs drug vehicle. (B) Representative flow cytometry histogram and quantitative results for binding of the antibodies kim127 (indicating intermediate-affinity conformation of β2 integrins) and mAb 24 (indicating high-affinity conformation of β2 integrins) to human aged and nonaged neutrophils isolated from the peripheral blood of healthy volunteers and stimulated with PBS or LPS. Mean ± SEM for n = 4-6; ^#P < .05 vs nonaged. AF, Alexa Fluor; PE, phycoerythrin.