Response to interferon-α treatment correlates with recovery of blood plasmacytoid dendritic cells...

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Journal of Hepatology 47 (2007) 751–759

Response to interferon-a treatment correlates with recovery of bloodplasmacytoid dendritic cells in children with chronic hepatitis Bq

Zheng Zhang1, Hongfei Zhang2, Dawei Chen2, Jinxia Yao1, Junliang Fu1,Lei Jin1, Fu-Sheng Wang1,*

1Research Center for Biological Therapy, Beijing 302 Hospital, Beijing 100039, China2The Fifth Clinical Department, Beijing 302 Hospital, Beijing 100039, China

Background/Aims: To investigate whether dendritic cell changes are associated with the efficacy of interferon-a treat-

ment we longitudinally analyzed circulating dendritic cells in children chronically infected with hepatitis B virus (HBV)

undergoing interferon-a treatment.

Methods: Thirty-one children with chronic hepatitis B (CHB) received interferon-a antiviral treatment for 52 weeks.

Myeloid and plasmacytoid dendritic cell (pDCs) frequency and function were analyzed at weeks 0, 2, 12, 24, 36 and 52

in 22 CHB patients.

Results: All patients exhibited an initially rapid decrease of circulating pDC numbers and CpG-induced endogenousinterferon-a production within 2 weeks of interferon-a treatment. Subsequently, all responders displayed a continuous

increase of both pDC numbers and function peaking around week 12. These responses were consequently accompanied

by viral clearance, hepatitis B e antigen seroconversion, and the improvement of circulating myeloid dendritic cells and

type 1 T helper cytokine levels. However, non-responders lacked these sequential responses compared with responders.

Conclusions: pDCs may actively correlate with interferon-a therapy-induced viral clearance in pediatric patients with

CHB. The recovery of blood pDC number and function may represent a prognostic marker for favourable response to

interferon-a treatment in chronic hepatitis B.

� 2007 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.

Keywords: Children; Hepatitis B virus; Dendritic cells; Plasmacytoid dendritic cells; Interferon-a; Antiviral therapy;

Response

0168-8278/$32.00 � 2007 European Association for the Study of the Liver.

doi:10.1016/j.jhep.2007.07.019

Received 15 February 2007; received in revised form 2 July 2007;

accepted 12 July 2007; available online 14 September 2007

Associate Editor: G.K.K. Lauq The authors who have taken part in the research of this paper

declared that they have no relationship with the manufacturers of thedrug involved either in the past or present and they did not receivefunding from the manufacturers to carry out their research. Theyreceived funding from the National Key Basic Research Program ofChina (No. 2006CB504305) and the National Science Fund forDistinguished Young Scholars (No. 30525042).

* Corresponding author. Tel./fax: +86 010 6387 9735.E-mail address: [email protected] (F.-S. Wang).

1. Introduction

The host immune response to hepatitis B virus (HBV)is a critical factor in determining the outcome of HBVinfection [1]. During the natural course of HBV infec-tion, patients with acute, self-limiting hepatitis B candevelop multiple and strong virus-specific T cellresponses, but these responses are weak and narrow inchronic HBV carriers [2–4]. Antiviral therapy-inducedhost immune responses against HBV also exhibit a cru-cial role in viral clearance [5–15]. Lamivudine [5] andadefovir [6] treatment can transiently restore T cellresponsiveness and improve myeloid dendritic cell

Published by Elsevier B.V. All rights reserved.

mailto:[email protected]

752 Z. Zhang et al. / Journal of Hepatology 47 (2007) 751–759

(mDC) numbers and functionality in chronic hepatitis B(CHB) patients. Interferon-a (IFN-a), the first approveddrug for CHB treatment, has been demonstrated to beimportant in promoting intrahepatic CD8 T-lymphocyteresponses and systemic Th1 immune responses [7,8].IFN-a therapy can also up-regulate CD14 expressionon intrahepatic macrophages in CHB patients [9] andcause specific IgG1/IgG3 subclass responses in patientswith viral responses but not in patients with viral non-responses [10]. These studies indicate that the hostimmune state may play an important role in determiningthe host responsiveness to antiviral therapy. Clinically,however, only around 30% patients with CHB generateeffective responses to antiviral IFN-a therapy, andapproximately 60–70% patients fail to control persistentHBV replication even while receiving IFN-a therapy.The immune mechanisms underlying the differencesbetween responders and non-responders deserve to beinvestigated further.

Dendritic cells (DCs), being the most efficiently pro-fessional antigen-presenting cells, orchestrate innateand adaptive immunities against invading pathogens[11]. In humans, DCs can be generally divided intomDCs and plasmacytoid dendritic cells (pDCs). In par-ticular, pDCs represent key cells in innate defense andregulation of adaptive immune responses in responseto viral infection [12]. Under normal physiological con-ditions, pDCs circulate in the blood and reside in lym-phoid organs. Upon viral stimulation, pDCs speciallyproduce large amounts of endogenous type 1 IFNs pri-marily via ligation of toll-like receptor (TLR) 7 and 9,and then differentiate into DCs and induce an IFN-dependent maturation of mDCs and further drive Th1responses [13–15].

Several studies have suggested that functionallyimpaired DCs may mediate host-specific T-cell immunesuppression favoring viral persistence during chronicHBV infection [6,16–19]. Our recent study has shownthat intrahepatic DC subsets correlate closely withplasma HBV loads and serum ALT levels in pediatricpatients with CHB [19]. However, little is known regard-ing the prognostic value of intrahepatic DCs to theresponse to IFN-a therapy. Limitations exist for serial

Table 1

Baseline characteristics of responders versus non-responders

Characteristics Healthy controls

Cases 28Age (year) 10 (4–15)Sex (m/f) 19/9HBV genotype (c/b) NAWBC (cells/ll) 3725 (2850–4130)ALT (U/L) 21 (10–37)HBV DNA (104 copies/ml) NA

NA, not applicable. Data are median and range.* P < 0.05, compared with responders.

analysis of intrahepatic DCs, therefore, this study wasundertaken to evaluate the relationship between periph-eral DCs and response to IFN-a treatment. We foundthat the recovery in numbers and function of circulatingpDCs closely correlate with a better response to IFN-atherapy, which probably indicates that pDCs may repre-sent a prognostic marker for evaluation of the efficacy ofIFN-a treatment for pediatric CHB patients. Our find-ings will extend our insight of DCs into understandingimmune pathogenesis in CHB patients.

2. Patients and methods

2.1. Patients

Thirty-one children with CHB, who have been well described pre-viously regarding immune active status and meet the antiviral stan-dards for IFN-a treatment [19], were randomly enrolled in thisstudy. Informed consent was obtained by their parents or legal guard-ians, in accordance with Institutional Review Board guidelines for theprotection of human subjects. Blood samples from 28 healthy childrenserved as normal controls (Table 1).

All patients were assigned to receive recombinant human IFN-a1balone at a dose of 3 MU/m2 via intramuscular injection, 3 times a weekfor 12 months. Blood samples from all patients were evaluated seriallyprior to and 2 weeks after onset of IFN-a treatment in hospitalization.In out-patient clinics, all patients were evaluated for clinical parame-ters including plasma HBV DNA, serum alanine aminotransferase(ALT) levels and anti-HBV markers; however, there were 22 patientswho simultaneously received evaluation of DCs during the whole per-iod of IFN-a treatment (Fig. 1a), 9 other patients dropped out fromfollow-up investigation of DC. Complete response to IFN-a treatmentwas confirmed at the end of treatment if HBeAg seroconversion (orloss of serum HBeAg), serum HBV DNA below detectable levelsand serum ALT level normalization were found. Patients who didnot meet the described requirements were defined as non-responders.

2.2. FACS analysis of peripheral DC subset frequency and

surface molecule expression

The peripheral DC subset frequency was analyzed using protocolspreviously described by our team with minor modification [19]. Inbrief, freshly isolated peripheral blood mononuclear cells (PBMCs)were incubated with anti-lineage-1-FITC, anti-HLA-DR-PerCP andanti-CD11c-APC (BD Pharmingen, San Jose, CA) or anti-CD123-APC (Miltenyi Biotec, Germany). Anti-CD86-PE or correspondingisotype IgG-PE were added separately to each tube and incubatedfor 20 min at 4 �C. The cells were fixed and analyzed by FACSCaliburand CellQuest software (BD Biosciences, San Jose, CA). At least

Responders Non-responders

11 2011.0 (3–15) 10.5 (5–15)10/1 12/810/1 19/13978 (2793–5167) 4436 (2703–5550)140 (45–659) 120 (42–665)132 (3.2–9150) 581 (7.91–30400)*

Fig. 1. Serological and virological responses to IFN-a therapy in HBV infected pediatric patients. (a) The longitudinal study schedule. The arrows below

the axis represent sampling point times. (b and c) Responders (n = 0) exhibited sustained serum plasma HBV DNA below the detectable levels (b, left) and

the normalization of serum ALT levels (c, left) within 12 months of IFN-a treatment, while non-responders (n = 11) maintained high levels of plasma HBV

DNA (b, right) and most non-responders had elevated serum ALT levels (c, right).

Z. Zhang et al. / Journal of Hepatology 47 (2007) 751–759 753

200,000 cells per run were acquired. The absolute numbers of circulat-ing DC subsets were calculated as per the formula that is the counts ofDCs (cells/ll) – (the DC frequency of PBMCs) · (lymphocyte cellcount/ll + monocyte cell count/ll). Lymphocyte and monocyte countswere determined by an automated differential blood count.

2.3. Cytokine assays of peripheral DC subsets and serum

IFN-c and TNF-a measurements

The cytokine-releasing capacity of peripheral DC subsets wasalso analyzed using protocols previously described by our team[19]. In a pilot experiment, peripheral mDCs and pDCs were iso-lated from three healthy children and two pediatric CHB patientsusing CD1c (BDCA-1) and BDCA-4 Dendritic Cell Isolation Kit(Miltenyi Biotec, Germany), respectively. Isolated mDC and pDCpopulations were greater than 95% in purity, while isolated negativefraction contained few DCs (less than 0.01%). The freshly preparedPBMC, mDC-depleted PBMC and isolated mDC, or pDC-depletedPBMC and isolated pDC populations were stimulated with poly I:Cor CpG 2216 for 24 h, respectively. Culture supernatants were quan-titated for IL-12 and IFN-a by standard ELISA. Serum IFN-c andTNF-a levels were also measured with commercial ELISA kits (Bio-source, Nivelles, Belgium). Sensitivity of the assays for these cyto-kines was 10 pg/ml.

2.4. Virological assessment

The virological assay protocol was performed according to ourrecent description [19]. The cut-off value was 500 copies/ml.

2.5. Statistical analysis

All data are summarized as median and range, and were analyzedusing SPSS software. Non-parametric Mann–Whitney U test was usedto compare data between two groups. A value of P < 0.05 was consid-ered statistically significant.

3. Results

3.1. Serological and virological responses to IFN-atherapy

At the end of IFN-a treatment, 35.5% (11/31) ofpatients exhibited a complete response indicated byHBeAg seroconversion (8/11 patients) or loss of serum


HBeAg (3/11 patients), serum HBV DNA below detect-able levels and the normalization of serum ALT levels.No patient exhibited loss of serum HBsAg. In thesepatients, 22/31 patients were serially sampled and evalu-ated for both clinical parameters and DC subsets,

Fig. 2. Rapid recovery of number and function of circulating pDCs correlate

Representative FACS dot plots of the fluctuations of direct ex vivo pDC and mD

alteration for the number of lymphocytes and monocytes in responders and no

pDC numbers (c) and pDC-derived IFN-a production (e) was observed in al

treatment. (d and f) Responders exhibit a similar pattern to non-responders in c

IFN-a treatment. (g) Representative data of CD86 expression on pDCs and mD

histograms represent CD86 staining; open histograms represent staining of i

expression. (h) Pooled data of CD86 expression on pDCs and mDCs in respond

treatment. Peak values are depicted at median 12 weeks. * compared with res

including 10 responders and 12 non-responders(Fig. 1a). As shown in Fig. 1b, plasma viral loadsdecreased to undetectable levels in 5/10 responders after12 weeks of therapy. The other 5 responders saw adecrease over the course of the remaining 9 months. In

s with responsiveness to IFN-a therapy in CHB pediatric patients. (a)

C frequencies in one responder and one non-responder. (b) Longitudinal

n-responders during IFN-a treatment. (c and e) A significant rebound of

l responders (n = 10) but not in non-responders (n = 11) during IFN-airculating mDC counts (d) and mDC-derived IL-12 production (f) during

Cs from a responder and a non-responder at various time points. Closed

sotype controls. Numbers in histograms represent percentage of CD86

ers (n = 6) and non-responders (n = 8) at various time points after IFN-aponders at same time point. P values are indicated.


contrast, a partial reduction of viral loads was observedin non-responders throughout the 12-month period ofIFN-a therapy. Accordingly, serum ALT had alsodecreased to below normal levels in all responders and6/11 non-responders by the end of therapy (Fig. 1c).Interestingly, we did not find ALT flare for thesepatients at all time points.

3.2. The circulating pDC recovery in number and function

correlates with the response to IFN-a therapy

To monitor the serial fluctuations of peripheral pDCsand mDCs in all patients undergoing antiviral IFN-atreatment, direct ex vivo pDC and mDC frequencywas analyzed using flow cytometric assay. The represen-tative dot plots of DC subset evaluation for individualresponder and non-responder are shown in Fig. 2a.We found circulating pDC numbers promptly declinedto the minimal level at 2 weeks in all children followingthe start of IFN-a treatment. Subsequently, respondersexhibited a rapid increase of pDC numbers, indicatinga reverse ‘‘V’’ type change with a maximal peak (median5.85 cells/ll [range 3.1–11.6 cells/ll]) after median 12weeks (range 9–16 weeks) of antiviral treatment. How-ever, non-responders often exhibited a persistent declineof pDC counts during the same period of investigation

Fig. 3. Time-course analysis of peripheral DC subsets and serum Th1 cytokine

clinical parameters, peripheral DC subsets and serum Th1 cytokines are depic

recovery of circulating pDC numbers and pDC-derived IFN-a production in re

seroconversion and the loss of plasma HBV DNA levels. These responses are s

Th1 cytokine levels. Non-responders showed no such changes.

(Fig. 2c). In contrast, mDC numbers in both respondersand non-responders slowly, but persistently decreasedafter administration of IFN-a treatment although therewere higher numbers in responders than in non-responders at the end of treatment (P < 0.05, Fig. 2d).Also, we found that no significant differences of lym-phocyte and monocyte counts were observed betweenresponders and non-responders at all time points,although patients displayed a slow and persistentdecrease for leukocyte counts after administration ofIFN-a treatment, in particular for peripheral monocytecounts (Fig. 2b).

We investigated the dynamic alterations of TLRligand-induced cytokine production by circulating DCsin these patients throughout the period of IFN-a treat-ment (Fig. 2e and f). At first, through directly performingDC subset depletion assay in three healthy children andtwo pediatric CHB patients enrolled in our study, it wasfound that depletion of mDCs or pDCs from freshPBMCs markedly reduces poly I:C-induced IL-12 orCpG-induced IFN-a production by more than 95%;while isolated mDCs (or pDCs) can almost produce thesame amount of IL-12 (or IFN-a) as the PBMCs thatcontain equal amount of DC subsets, respectively (datanot shown). These evidences indicate that poly I:C-induced IL-12 is dependent on mDC compartment and

s from CHB patients following IFN-a treatment. Representative data of

ted in two responders (a and b) and two non-responders (c and d). The

sponders simultaneously accompanies viral clearance, including HBeAg

ubsequently accompanied by increased circulating mDC levels and serum


CpG-induced IFN-a on pDCs in PBMCs. Therefore, welongitudinally detected peripheral DC function usingTLR ligands stimulating PBMCs. We found that CpG-induced IFN-a production rapidly decreased to mini-mum levels from baseline by 4.7-fold in all patients at 2weeks following treatment initiation. After 2 weeks,CpG-induced IFN-a production also exhibited a reverse‘‘V’’ type recovery in responders, with a median peak of229.9 pg/ml seen at a median 12 weeks after the treat-ment. This result significantly differed from that innon-responders, who had persistently low levels ofpDC-derived IFN-a production at this time point(Fig. 2e). In contrast, poly I:C-induced IL-12 productionwas found to have a variable extent of change in bothresponders and non-responders within the first 12-weekperiod of therapy. After that, poly I:C-induced IL-12production began to rise and maintained on higher levels

Fig. 4. Baseline levels of circulating DC subsets and serum Th1 cytokines in rela

of peripheral mDC-derived IL-12 production (d) and serum IFN-c concentrat

observed in circulating pDC (a) and mDC (c) counts and pDC-derived IFN-a pr

at baseline. HC, Healthy controls; R, responders to IFN-a therapy; NR, non-r

in responders; while non-responders displayed a contin-uous decrease in poly I:C-induced IL-12 production untilthe end of treatment (P < 0.05, Fig. 2f). We also foundthat serum IFN-c and TNF-a decreased in most patientswithin 2 weeks after the initiation of IFN-a treatment.However, responders exhibited a reverse ‘‘V’’ type recov-ery with peaks of IFN-c levels at median 30 weeks (range21–43 weeks) after treatment; while non-responderslacked this rebound at this time point (data not shown).

In addition, we longitudinally analyzed CD86 expres-sion on peripheral DC subsets (Fig. 2g) and found fewdifferences between mDCs and pDCs at the time pointsexamined (Fig. 2h). Thus, the dynamic DC subset num-bers and cytokine production in responders differed sig-nificantly from those of non-responders although bothpatient cohorts received the same 12-month IFN-atreatment.

tion to the response to IFN-a therapy. Responders exhibited higher levels

ion (e) than non-responders at baseline. No significant differences were

oduction (b) and serum TNF-a (f) between responders and non-responders

esponders to IFN-a therapy; P values are shown.


3.3. Time course analysis of DC subsets in relation to viral

clearance and ALT normalization

To determine the association between increased DCsubset numbers and Th1 cytokines with viral clearanceand ALT normalization, the sequent events were ana-lyzed in the HBV-infected children undergoing 12months of IFN-a therapy. All 10 responders showed asignificant rise in CpG-induced IFN-a production aftermedian 12 weeks of treatment (Fig. 3a and b). This peakof CpG-induced IFN-a production occurred simulta-neously (n = 7) or preceded (n = 3) plasma HBV DNAloss and HBeAg seroconversion. After the peak, therewere significant increases in poly I:C-induced IL-12 pro-duction and serum IFN-c and TNF-a levels around 36weeks. In non-responders, CpG-induced IFN-a produc-tion was quickly reduced after the initiation of treatmentand maintained persistently low levels during the follow-up period, regardless of the alteration in poly I:C-induced IL-12 production or serum IFN-c and TNF-alevels (Fig. 3c and d).

3.4. Baseline DC subsets correlate with effective response

to IFN-a therapy

We retrospectively analyzed the baseline properties ofDC subsets and serum Th1 cytokines in relation toresponse to IFN-a therapy (Fig. 4). We found that therewere similar amounts of circulating pDC and mDCnumbers between responders and non-responders atbaseline (Fig. 4a and b), but peripheral pDC numberswere significantly decreased in CHB individuals at base-line compared with healthy individuals (both P < 0.05;Fig. 4a). The pre-treatment mDC-derived IL-12 produc-tion in responders (median 794.8 pg/ml [range 259.4–1113.0 pg/ml]) was also significantly higher than thatof non-responders (median 376.7 pg/ml [range 17.2–1315.5 pg/ml]) (both P < 0.05; Fig. 4d). However, nosignificant differences of pre-treatment CpG-inducedIFN-a production were found between responders andnon-responders (Fig. 4c).

Moreover, we found that patients have significantlyhigher levels of pre-treatment serum Th1 cytokines thanhealthy subjects (Fig. 4e and f). When compared withresponders, non-responders have significantly lowerpre-treatment serum IFN-c but no difference for serumTNF-a level between the two groups (Fig. 4e and f).

3.5. Clinical features at baseline in relation to response to

therapy

Differences in pre-treatment clinical characteristicsbetween responders and non-responders are shown inTable 1. The pre-treatment plasma HBV DNA level waslower in the responder group (median 1.32 · 106 copies/ml) than non-responder group (median, 8.81 · 106 cop-

ies/ml; P < 0.05). The pre-treatment serum ALT did notdiffer between responders and non-responders.

4. Discussion

This study first characterized the dynamics of circu-lating DC subsets and revealed their correlation withHBV clearance in chronic HBV-infected pediatricpatients undergoing IFN-a treatment. We found thatthe complete responders to IFN-a therapy exhibitedan initially rapid decrease and then recovery of circulat-ing pDC numbers and IFN-a production; while non-responders lacked this alteration. Within two weeks ofexogenous IFN-a treatment, pDC-derived IFN-a pro-duction initially rapidly decreased, possibly indicatingnegative feedback regulation in these patients [20], whilethe initial rapid decrease of pDC numbers may beexplained as possible redistribution of pDCs into theinflammatory liver [19,21]. Previous data from miceindicate that recombinant IFN-a can drive the accumu-lation of macrophage inflammatory protein (MIP)-1a-producing cells into the liver [22]. PDCs can produceMIP-1a after stimulation with CpG, CD40L or viruses[23,24] and MIP-1a has been found in liver infiltratingmononuclear cells from HCV-infected patients receivingIFN-a2a therapy, supporting the redistribution asser-tion [25]. Indeed, type 1 IFNs are necessary for themigration of pDCs in vivo [26]. Thus, IFN-a may playa role in inducing pDC migration from the blood tothe liver. Together with previous reports demonstratingthat IFN-a treatment could significantly increase intra-hepatic CD8 T-cell but not CD4 T-cell numbers andCD14 expression on liver macrophages in responders[7,9], our data suggest that IFN-a treatment mayoptionally recruit peripheral lymphocytes includingpDCs into the liver, so as to enhance viral removaland reduce potential liver damage. In this study, how-ever, we must cautiously interpret the small differencesbetween responders and non-responders in peak pDCcount, which may be caused by our small cohortpatients. In addition, although we did directly monitorDC function in vitro in three healthy children and twopediatric CHB patients and confirmed that the maincontributors of IFN-a and IL-12 production are pDCsand mDCs, respectively, we lacked the correspondingdata of direct DC function analysis for the majority ofthese patients because it is difficult to longitudinallyobtain enough volume of peripheral blood for each ofthe all enrolled children. Therefore, future comprehen-sive investigation needs to focus on the direct functionalanalysis for DC subsets in a larger cohort of HBV-infected patients undergoing IFN-a therapy for furtherelucidation of pDC role in the disease.

After 2 weeks of IFN-a treatment, all respondersexhibited an increase of pDC numbers and IFN-a pro-


duction peaking around week 12. These responses wereaccompanied by viral clearance, HBeAg seroconversion,and improved circulating mDC numbers and Th1 cyto-kine levels. These sequential responses were uniquelyfound in responders but not in non-responders. Duringthis phase, the peripheral pDC restoration may repre-sent the completion of pDC migration into the liverwhere they function as linkers between innate and adap-tive immunity [13]. Interestingly, pDC recovery duringIFN-a therapy occurred almost simultaneously withthe peak level of intrahepatic CD8 T-lymphocyteresponses [7] and circulating HBeAg-specific T cell pro-liferation [8], but before the peak level of serum IL-12concentrations following IFN-a treatment [8]. Thissequential timing strongly implies that pDCs areinvolved in the initial immune responses as a result ofIFN-a therapy. Several recent findings also support thenotion that pDCs can induce virus-specific CD8 T-cellantiviral responses [14,27] and the bystander maturationof mDCs [15]. Thus, our data suggest that a strong pDCrecovery may be an important factor in HBV clearance[28–30], and presents a marker for favorable responsesto IFN-a treatment in patients with CHB.

Knowing more factors predicting response to IFNtreatment may be useful in the decision to continue ormodify therapy for CHB patients. Some studies indicatethat responsiveness to IFN-a treatment of CHB patientsis dependent on many factors, such as genotype of HBV,pretreatment HBV DNA levels, pretreatment ALT lev-els, and so on [31,32]. In line with these studies [31,32],our observations also indicate that the patients withlow baseline HBV DNA levels are able to generate afavorable response to IFN-a. More importantly, wehave highlighted that higher levels of poly I:C-inducedIL-12 production and serum IFN-c levels at baselinemay also predict a favorable response to IFN-a treat-ment. These data are in agreement with previous studiesshowing that high serum IL-12 peaks are only present inresponders [8]. These data suggested that pre-treatmentimmune status of the host may also determine the out-come of IFN-a therapy-induced HBV clearance [33].

In summary, the present study suggests that chroni-cally HBV-infected pediatric patients favorablyresponding to IFN-a therapy are characterized by aprominent circulating pDC recovery. Therefore, pDCrecovery may be able to serve as an indicator forpatients capable of responding to IFN-a treatment.These novel findings suggest that boosting pDC func-tion should be considered as a new therapeutic strategyfor CHB patients.

Acknowledgements

Authors appreciate Prof. Yong-Jun Liu (Center forCancer Immunology Research, MD Anderson CancerCenter, University of Texas, Houston, TX, USA) for

his valuable comments and critical review of this manu-script. This study was supported by grants from the Na-tional Key Basic Research Program of China (No.2006CB504305) and the National Science Fund for Dis-tinguished Young Scholars (No. 30525042).

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Response to interferon-α treatment correlates with recovery of blood plasmacytoid dendritic cells...

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