Concentration and time-dependent effects of PF4 on the surface expression of carboxypeptidase M/MAX1 on human monocytes.

(A) Concentration-kinetics. Monocytes were cultured for 72 hours in the presence of increasing concentrations PF4 (•) or left untreated (-----). Cells were subsequently analyzed by flow cytometry for carboxypeptidase M/MAX1 expression, given as median fluorescence intensity as described under “Materials and Methods.” (B) Time-kinetics. Monocytes were incubated for different time periods in the absence (○) or presence (•) of a constant concentration of PF4 (4 μmol/L) and analyzed as described above. Data from 1 representative experiment out of 3 are shown.