Buprenorphine decreases CCL2-mediated binding of mature monocytes to ICAM-1 but not to VCAM-1. Calcein-AM labeled mature monocytes were untreated or treated with CCL2 (200 ng/mL) or with CCL2 plus buprenorphine (40 nM) (C+B), and added immediately to wells of a 96 well plate coated with Fc-ICAM-1 (10 μg/mL) or Fc-VCAM-1 (10 μg/mL). After 10 minutes of incubation at 37°C, wells were washed and fluorescence measured using a fluorimeter. (A) Fc-ICAM-1 and (B) Fc-VCAM-1 adhesion assays. Data are expressed as mean fold change over base line adhesion (untreated cells), which was set to one and depicted as a dotted line, ± SD. n = 11 independent donors. &&p<0.005 compared to base line, **p<0.005, C+B compared to CCL2, N.S no statistical significance.