Abstract
[Objective] Dendritic cells (DC) are one of antigen-presenting cells and play an essential role in the immune system. Recently, tumor immunotherapy using DC has been reported. However, whether immune response of DC is affected by radiotherapy remains to be eludicated. We therefore in an attempt to clarify the effect of radiation on the differentiation of DC, we focused on monocytes that could differentiate into myeloid DC, while also investigating whether X-irradiated monocytes could differentiate into DC. [Methods] Monocytes were separated from buffy coat, and then were exposed to X-ray of 5 Gy. For the preparation of immature DC (iDC), X-irradiated monocytes were cultured in RPMI 1640 supplemented with 2% human AB serum, rhGM-CSF and rhIL-4 for 5 days. To prepare mature DC (mDC), iDC were further incubated in the presence of rhTNF-alpha for 4 days. The phenotype of iDC and mDC and the phagocytic activity of iDC were analyzed by flow cytometry. [Results] The iDC and mDC generated from X-irradiated monocytes expressed each type of DC specific surface antigen. However, the expression of CD40 on iDC and CD80 on mDC derived from X-irradiated monocytes was higher than of the control, respectively. Furthermore, the degree of phagocytosis of iDC was also observed to be lower than of the control. [Discussion] Our results demonstrated that X-irradiated monocytes could differentiate into DC. In addition, since the expression of CD40 increases while phagocytosis decrease during maturation, these findings suggest the possibility that X irradiation may therefore enhance DC maturation.
