Monocyte-derived dendritic cell function in chronic hepatitis C is impaired at physiological numbers of dendritic cells

Abstract

Monocyte-derived dendritic cells (MoDCs) are a promising cellular adjuvant for effector immune responses against tumours and chronic viral infections, including hepatitis C virus (HCV). If autologous DC therapeutic approaches are to be applied in persistent HCV infections in patients, it is important to have an unambiguous understanding of the functional status of the cell type used, namely MoDCs from patients with chronic hepatitis C (CHC) infection. Because of conflicting published reports of either impaired or normal MoDC function in CHC infection, we re-examined the ability of MoDCs from CHC and normal healthy donors (NHD) to mature to an inflammatory stimulus [tumour necrosis factor (TNF)-alpha] and their subsequent functional capabilities. Expression of maturation-associated phenotypic markers [human leucocyte antigen (HLA)-DR, CD83, CD86, CD40], allostimulatory capacity in mixed lymphocyte reactions (MLRs) and CD40-ligand-induced cytokine and chemokine generation were compared in CHC- versus NHD-MoDCs. TNF-alpha-stimulated CHC-MoDCs up-regulated phenotypic markers, but to significantly lower levels than NHD-MoDCs. At physiological ratios of DCs to T cells, CHC-MoDCs were less allostimulatory than NHD-MoDCs, but not when DC numbers were substantially increased. CHC- and NHD-MoDCs generated equivalent amounts of cytokines [TNF-alpha, interleukin (IL)-1beta, IL-6, IL-12p70, IL-15, IL-10] and chemokines [interferon-inducible protein (IP)-10, macrophage inflammatory protein (MIP)-1alpha, regulated upon activation, normal T expressed and secreted (RANTES)] after CD40 ligation. Because the functional defect was not apparent at high MoDC : T cell ratios, autologous MoDC therapy with sufficiently high numbers of DCs could, in theory, overcome any impairment of MoDC function in CHC.

Fig. 2

The allostimulatory capacity of monocyte-derived dendritic cells (MoDCs) cultured from patients with chronic hepatitis infection (CHC) is impaired at low DC : T cell ratios compared with MoDCs from normal healthy donors (NHD). The percentage of allogeneic CD4⁺ T cells that proliferated in response to the presence of varying numbers of (a) immature MoDCs (iDCs) or (b) tumour necrosis factor (TNF)-α-matured MoDCs (mDCs) is shown. Each point represents the mean ( s.d.) of results from 10 (CHC) or 13 (NHD) individuals. *P < 0·05.

Fig. 1

Impaired up-regulation of maturation markers following tumour necrosis factor (TNF)-α treatment of monocyte-derived dendritic cells (MoDCs) from chronic hepatitis C (CHC, n= 10) patients compared with normal healthy donor MoDCs (NHD, n= 10, right column of graphs). The left and middle columns of graphs show representative fluorescence activated cell sorter analysis histograms of NHD and CHC donors, respectively; x-axes represent fluorescence intensity and event counts are indicated on the y-axes. Grey-shaded histograms are immature MoDCs and open histograms are TNF-α-matured MoDCs. The graphs in the right column summarize the group results. Values are expressed as fold-increase in mean fluorescence intensity after TNF-α treatment. *P < 0·05.

Fig. 3

Monocyte-derived dendritic cells (MoDCs) cultured from chronic hepatitis C (CHC, n = 11 or 12) patients show no impaired cytokine or chemokine response to CD40 ligation compared with MoDCs from normal healthy donors (NHD, n = 11–15). Immature MoDCs (iDCs) or tumour necrosis factor (TNF)-α-matured DCs (mDCs) were stimulated with CHO cells transfected with human CD40 ligand. Wild-type CHO cells served as a control treatment and stimulated no detectable cytokine or chemokine response (data not shown).