Effect of LPS preincubation on ICAM-1 (CD54) expression by stimulated monocytes. The binding of fluorescein isothiocyanate (FITC)-labeled CD54 antibodies to monocytes is shown. An overlay histogram is given to compare membrane expression of CD54 on unstimulated cells (filled histogram), monocytes stimulated with IFN-γ (300 U/mL) (A) or IFN-γ/LPS (B) (open histogram, thin line) and IFN-γ (A) or IFN-γ/LPS (B) stimulated monocytes preincubated with LPS for 24 hours (open histogram, thick line). One representative experiment of 3 is depicted.