Stromal-derived factor-1 up-regulated the expression of MIC on mouse keratinocyte stem cells

Although previous studies have demonstrated that stromal-derived factor-1 (SDF-1) played a key role in chronic graft dysfunction (CGD), the precise mechanisms underlying this process are not clear. In this study, SDF-1 was injected into keratinocyte stem cells (KSCs) which were isolated and purified from neonatal C57BL/6 (H-2b) mice. Adenylyl cyclase (AC) activity of KSCs was measured and expressions of the human major histocompatibility complex (MHC) class I chain-related antigens A and B (MICA, MICB) detected by immunofluorescence. Cultured KSCs were negative for IA/IE MHC class II molecules by immunofluorescence, indicating the absence of any contamination with Langerhans cells and certifying the purity of KSCs. Over a 7-day culture period, SDF-1 up-regulated AC activity to 2.783 +/- 0.799, which was higher than that of the control group (1.290 +/- 0.476; P < .01). Immunostaining showed that KSCs expressed increased amounts of MICA protein (0.790 +/- 0.134 versus 0.200 +/- 0.022; P < .01) and MICB protein (0.610 +/- 0.832 versus 0.230 +/- 0.016; P < .01). Mixed lymphocyte reaction assays showed that KSCs cultured with SDF-1 injection for 7 days stimulated allogeneic T-cell proliferation. The data indicated that SDF-1 may accelerate the ultimate rejection of allogeneic keratinocytes by enhancing MIC through the AC signal pathway.