METHODS: cDC were isolated from naïve C57BL6 mice by immunomagnetic selection. BAL CD49d+ and CD49d–PMN were isolated 3 days post SeV inoculation using flow sorting. CD49d+PMN were cultured in complete RPMI-10 for 48 hours and supernatant collected. Using a SpeedVac, supernatant was concentrated 2 fold. CD49d–PMN and cDC were co-cultured with increasing CD49d+PMN supernatant concentrations. After 48 hours, cDC FcεRI expression was measured by flow cytometry. Data are presented as net MFI from IgG control.
RESULTS: Un-concentrated CD49d+PMN supernatant led to a net MFI expression of FcεRI on cDC of 95.0 (n=1). Co-culturing cDC with 2 fold concentrated CD49d+PMN supernatant led to a net MFI of 276.5±41.5 (mean±SEM, n=2), demonstrating a direct relationship between FcεRI expression and CD49d+PMN supernatant.
CONCLUSIONS: CD49d+PMN appear to express a soluble factor that induces expression of cDC FcεRI in a dose dependent fashion, when cultured with CD49d–PMN. Further studies will be aimed at identifying this soluble factor, and developing strategies to inhibit it therapeutically.