Figure 3

Release of opioid peptides from monocytes in response to TLR4 but not TLR2 stimulation. (A, B) Monocytes were isolated from human buffy coats and purified for CD14. Release of β-endorphin (β-END) was quantified after incubation for 15 or 120 min with different doses of LPS or Pam₃CSK₄ (n = 7–9, * p < 0.05, One way RM ANOVA, Student-Newman-Keuls). (C) Monocytes were separated into CD14⁺CD16^- and CD14⁺CD16⁺ monocytes. Expression of TLR2 (green line) and TLR4 (red line) was analyzed using flow cytometry in both populations. Isotype controls are shown (black line) (representative example, n = 3). (D) β-END content after lysis of unstimulated cells was measured by ELISA in these populations, CD14⁺CD16^- (black) and CD14⁺CD16⁺ (black striped) monocytes (n = 8, * p < 0.05 paired t-test) (E,F) CD14⁺CD16^- and CD14⁺CD16⁺ monocytes were stimulated for 15 min with 10 μg/ml LPS (red) compared to stimulation with solvent medium (black). β-END was analyzed in the supernatant (n = 8, * p < 0.05, paired t-test). All data are presented as MEAN ± SEM.