Figure 2. Morphine secretion from human primary neutrophils.

A . Typical dose-response curve of the morphine detection performed with the morphine-specific ELISA. B. Upper panel, Morphine secreted from neutrophils expressed as pg/ml. Morphine was quantified in culture medium after stimulating 20.10⁶ neutrophils with LPS (10 ng/ml, 6 h; n = 6) in presence or absence of Ca²⁺. Basal secretion levels were obtained from neutrophils incubated without LPS (6 h; n = 6). Lower panel, Efficiency of secretion was assessed by monitoring the secretion of lactoferrin (75 kDa, a marker of secondary granules) by Western blot analysis. C. Upper panel , Morphine was quantified in culture medium after stimulating 20.10⁶ neutrophils with IL-8 (50 nM, 7 min; n = 7) in presence or absence of Ca²⁺. Basal secretion levels were obtained from neutrophils incubated without IL-8 (7 min; n = 6). Lower panel, The efficiency of secretion was assessed by monitoring the secretion of lactoferrin (75 kDa, a marker of secondary granules) by Western blot analysis (50 µg). Amounts of secreted morphine in the LPS and IL-8 groups were statistically different from the two control groups (no LPS and IL-8; *: p<0.01 with a Mann-Whitney test after Bonferroni correction.