LBP lipid transfer activity is equal in plasma- and serum-derived FALP.

(A) LBP-catalyzed transfer of LPS to CD14 FALPs were mixed quickly with BODIPY-LPS and sCD14 in a 96-well plate at room temperature, and the increase in fluorescence was measured every 2 minutes for 50 minutes. The final concentration of LBP in pFALP and sFALP was 0.56 and 0.43 μg/mL, respectively. Final concentrations of sCD14 and BODIPY-LPS were 2 and 0.8 μg/mL, respectively. Controls included BODIPY-LPS incubated with pFALP or sFALP alone (pFALP alone, sFALP alone), incubated with sCD14 alone (CD14 alone), or buffer alone (Buffer alone). The Y-axis represents arbitrary fluorescence units. (B) LBP-catalyzed transfer of LPS to HDL FALPs were mixed with BODIPY-LPS and rHDL at 37°C, and the increase in fluorescence was measured every 5 minutes for 4 hours. The final concentrations of the each component are: rHDL 100 μg/mL (expressed as apoAI content), BODIPY-LPS 0.6 μg/mL, and pFALP and sFALP 0.5 μg/mL of LBP. Further dilution of pFALP and sFALP to 0.25, 0.125, 0.06, and 0.03 μg/mL of LBP did not show any difference between pFALP and sFALP as well (data not shown). Controls were included as above, except that rHDL was used instead of sCD14. These experiments were repeated twice with similar results.