Abstract
[Objective] Dendritic cells (DCs) play a key role in the immune system. X-irradiated monocytes can differentiate into DCs, although some functions of DCs such as the matrix metalloproteinase-9 (MMP-9) activity are impaired in the DCs from X-irradiated monocytes (J. Radiat. Res., 49, 2008). In that study, we used TNF-α as maturation stimuli. The present study investigated whether the type of maturation stimulus influence DCs derived from X-irradiated monocytes using lipopolysaccharide (LPS) and a cytokine mixture (MIX). [Methods] Monocytes were separated from the buffy coat and exposed to X-rays at 0, 2, 5 and 10 Gy. To prepare immature DCs (iDCs), the irradiated monocytes were cultured in the presence of rhGM-CSF and rhIL-4. To prepare mature DCs, iDCs were stimulated with LPS or MIX (rhTNF-α, IL-1β, IL-6, PGE2) for 48 hr. The phenotype of the DCs was analyzed by flow cytometry and the MMP-9 activity was assayed by zymography. [Results and Discussion] When LPS was used as the maturation stimuli, the expression level of the co-stimulatory molecule CD80 and DCs' maturation marker CD83 on the DCs from X-irradiated monocytes was lower than that of the DCs from non-irradiated monocytes. However, no decrease was observed in the DCs stimulated by MIX. The MMP-9 activity in the culture supernatants was impaired in the DCs from the X-irradiated monocytes matured with LPS, whereas there was no large difference in those matured with MIX. These results suggest that the influences of X-irradiation on monocytes regarding the maturation of DCs may depend on the type of maturation stimulus.
