Increased extracellular pressure provides a novel adjuvant stimulus for enhancement of conventional dendritic cell maturation strategies

Dendritic cell (DC)-based vaccine strategies have gained increasing popularity in recent years. Methods for ex vivo generation of immunocompetent mature DCs still require optimization. DCs have been shown to phenotypically mature under elevated pressure. We compared the effects of pressure on DC maturation with LPS- and cytokine-stimulation. Human monocyte-derived immature or LPS- and cytokine-matured DCs were exposed to ambient or 40 mmHg increased pressure for 12 h, then assessed for expression of CD80, CD86, CD40, MHC-I/II, and inflammatory cytokine production. DCs were also evaluated for capacity to stimulate T-cell proliferation by co-culture with allogeneic lymphocytes. Pressure significantly increased cytokine production and expression of all surface molecules on immature DC other than MHC-I and CD40. Pressure/LPS-treated DCs displayed further upregulation of MHC-I, CD40, and IL-12p70. Cytokine-matured DCs appeared less responsive to pressure. T-cell proliferation correlated with MHC expression. Results suggest mechanical stimulation of DCs may provide a useful adjuvant to TLR-agonist maturation strategies.