Abstract:

Objective To study the effects of some cytokines such as TNF-α，IL-6 and IFN-γ as well as lipopolysaccharide on CD68 expression in HaCaT cells. Methods Human HaCaT keratinocytes were randomly divided into natural proliferation group （without stimulation）, IFN-γ-stimulated group, TNF-α-stimulated group, LPS-stimulated group and IL-6 stimulated group. The work concentration of TNF-α, IL-6, IFN-γ and LPS was 50 mg/L. HaCaT cells were collected after 24-hour treatment with the cytokines followed by the examination of CD68 expression with flow cytometry, immunohistochemistry and reverse transcription （RT）-PCR, respectively. Results Compared with untreated HaCaT cells, the count of CD68-positive cells was elevated in cells stimulated by TNF-α （t = 3.60, P < 0.01）, IL-6 （t = 3.93, P < 0.01）, IFN-γ （t = 2.38, P < 0.05） and LPS （t = 2.52, P < 0.05）, and the effect of TNF-α and IL-6 was stronger than that of IFN-γ and LPS. Among the four cytokines, only IL-6 enhanced the mean fluorescence intensity of CD68-positive cells （t = 8.34, P < 0.01）. After 24-hour treatment with TNF-α, IFN-γ and IL-6, CD68 expression was observed in the cytoplasm and on the membrane of HaCaT cells, and was stronger in cells treated with TNF-α and IL-6 than in those with the other cytokines. A significant increase was observed in the CD68 mRNA expression after 24-hour treatment with TNF-α （t = 4.34, P < 0.01）, IL-6 （t = 7.52, P < 0.01） and IFN-γ （t = 2.81, P < 0.05）; TNF-α and IL-6 showed a stronger promotive effect than IFN-γ. Conclusion IL-6, TNF-α, IFN-γ and LPS can upregulate the CD68 expression in HaCaT cells.

Key words: flow cytometric analysis