Abstract: Objective To study the dose- and time-effect relationship bet ween lipopolysaccharide (LPS) and CD14 expression in the cell line J774A.1 of mouse macrophages. Methods The cell line J774A.1 was stimulated with different doses of LPS，and the CD14 surface-positive cells from the cell line J774A.1 were detected by flow cytometry（FCM）45 min after stained with FITC-CD14 monoclonal antibody. The changes of CD14 surface expression in the cell line J774A.1 at different time（1,2,4,8 and 16 h）after stimulated with LPS were observed. After the best stimulant time was selected，the cell line J774A.1 was treated with different doses（1,10,50,100,500 and 1 000 μg·L^-1）of LPS and the changes of CD14 surface expression were observed. Results In view of time-effect，compared with control group（the positive rate was 12.50±3.71），LPS significantly enhanced the CD14 expression at 1，2 and 4 h after stimulation（the positive rates were 23.80±5.07，23.04±2.88 and 28.22±1.54,respectively） when the dose of LPS was 1 μg·L^-1 （P<0.01）. When the concentration of LPS was 10 μg·L^-1, CD14 expression strengthened at 1 and 2 h after stimulation（the positive rates were 40.85±6.05 and 26.63±6.17, respectively）（P<0.05，P<0.01）.LPS obviously stimulated CD14 expression at 1 h after stimulation（the positive rate was 47.40±2.85）when the dose of LPS was 50 μg·L^-1（P<0.01）. In the dose-effect, the stimulant effect of LPS occurred when LPS was administered only below the dose of 10 μg·L^-1 at 4 h after stimulation（P<0.01）. Conclusion LPS can significantly stimulate the expression of CD14 in the cell line J774A.1 below the dose of 50 μg·L^-1 within 4 h.

Key words: lipopolysacharides, antigens, CD14