Detection of microbial antigenic components of circulating immune complexes in HIV patients:Involvement in CD4^+ T lymphocyte count depletion

Objective:To investigate the prevalence of microbial antigenic components of circulating immune complexes amongst grades of CD4 T lymphocyte counts in HIV sero positive and seronegative participants.Methods:Polyethelene glycol(PEG-600) and buffering methods of precipitation and dissociation of immune complexes was used to generate immune solution from sera of 100 HIV sero-positive and 100 HIV sero-negative participants.These were categorized into 3 grades based on CD4 count:】 500 cell/mm,200-499 cell/mm3 and 【200 cell/mm3.The immune solutions were assayed using membrane based immunoassay and antibody titration, along side its unprocessed serum for detection of various microbial antigens and or antibodies. CD4 T cell counts were estimated using Patec Cyflow SL-3 Germany.Results:Antigenic component of immune complexes of various infectious agents was detected in 99 and 70 HIV seropositive and HIV sero-negative participants,respectively.In group A,there were 10 HIV positive participants,including 4(40.0%) had circulating immune complexes(CICs) due to Salmonella species only:1(10.0%) due to Salmonella-Plasmodium falciparum(P.falciparum),SalmonellaP. falciparum-HCV and P.falciparum antigens,respectively.In group B,45(45.4%) HIV seropositive participants with CICs had CD4 T lymphocyte count between 200-499 cells/mm^3.Out of these,20(44.4%) had CICs due to Salmonella species only:9(20%) due to Salmonella-P. falciparum.In group C,there were 44(44.4%) HIV sero-positive participants,including 3(6.8%) due to Salmonella species only:24(54.4%) due to Salmonella-P.falciparum:2(4.5%) due to P. falciparum only.Conclusions:In HIV sero-positive participants,presence of heterogeneity of Salmonella species-P.falciparum antigens was highly incriminated in CD4 count depletion but not homogeneity of malaria parasites antigens.Malaria parasites antigens only were incriminated in CD4^+ count depletion amongst HIV sero-negative participants.Before taking any decision on the management of HIV-1-positive individuals,their malaria and Salmonella paratyphi status should be assessed,but not malaria status alone.

Regulatory T cells suppress autoreactive CD4^+ T cell response to bladder epithelial antigen

AIM： To investigate the role of regulatory T （Treg） cells in CD4^＋ T cell-mediated bladder autoimmune infammation. METHODS： Urothelium-ovalbumin （URO-OVA）/OT-II mice, a double transgenic line that expresses the membrane form of the model antigen （Ag） OVA as a self-Ag on the urothelium and the OVA-specific CD4^＋ T cell receptor specifc for the I-Ab/OVA323-339 epitope in the periphery, were developed to provide an autoimmune environment for investigation of the role of Treg cells in bladder autoimmune infammation. To facilitate Treg cell analysis, we further developed URO-OVA^GFP-Foxp3/OT-II mice, a derived line of URO-OVA/OT-II mice that express the green fuorescent protein （GFP）-forkhead box protein P3 （Foxp3） fusion protein. RESULTS： URO-OVA/OT-II mice failed to develop bladder infammation despite the presence of autoreactive CD4^＋ T cells. By monitoring GFP-positive cells, bladder infltration of CD4^＋ Treg cells was observed in URO-OVA^GFP-Foxp3/OT-II mice. The infiltrating Treg cells were functionally active and expressed Treg cell effector molecule as well as marker mRNAs including transforming growth factor-β, interleukin （IL）-10, fibrinogen-like protein 2, and glucocorticoid-induced tumor necrosis factor receptor （GITR）. Studies further revealed that Treg cells from URO-OVA^GFP-Foxp3/OT-II mice were suppressive and inhibited autoreactive CD4^＋ T cell proliferation and interferon （IFN）-g production in response to OVA Ag stimulation. Depletion of GITR-positive cells led to spontaneous development of bladder infammation and expression of inflammatory factor mRNAs for IFN-γ, IL-6, tumor necrosis factor-α and nerve growth factor in URO-OVA^GFP-Foxp3/OT-II mice. CONCLUSION： Treg cells specifc for bladder epithelial Ag play an important role in immunological homeostasis and the control of CD4^＋ T cell-mediated bladder autoimmune infammation.

小鼠CD4、CD8膜外区编码cDNA的克隆与表达

目的 克隆并表达小鼠CD4和CD8基因,以期制备其抗体为疫苗研究服务。方法 从小鼠脾细胞中提取总RNA,利用RT PCR技术克隆CD4、CD8α和CD8β膜外区片段的编码cDNA,利用谷光苷肽硫基转移酶 (GST)融合表达载体pGEX CS对其进行表达,利用聚丙烯酰胺凝胶电泳(SDS PAGE)和Westernblot对重组蛋白进行鉴定。结果 以小鼠脾细胞总RNA为模板,分别扩增出小鼠CD4、CD8α和CD8β膜外区片段的编码cDNA,将其插入表达载体pGEX CS,得到重组质粒pGEX CSCD4、pGEX CSCD8α和pGEX CSCD8β。将所获表达载体转化E.coliBL21,用IPTG诱导表达,SDS PAGE检测表明小鼠CD4、CD8α、CD8β片段均得到成功表达,其表达量可占菌体蛋白总量的 30%左右,且均可与抗GST抗体反应。结论 成功克隆、表达了小鼠CD4、CD8α和CD8β,为进一步制备抗体从而用于免疫学研究打下了基础。

Risk Factors, Clinical Features, Baseline Alanine Aminotransferase and CD4+ Count of Children with HIV Co-Infection with Hepatitis B and C at a Tertiary Hospital in Southwest Nigeria

Background: Human immunodeficiency virus and hepatitis B and C viruses are endemic in sub- Saharan African countries including Nigeria. Researchers have studied the burden of co-infection of HIV with hepatitis B and hepatitis C but the risk factors and clinical presentation have not been much addressed especially in children. Methodology: This was a prospective cross sectional study that determined the prevalence, risk factors, clinical features, baseline CD4+ count, CD4+ percentage, and alanine aminotransferase (ALT) of newly diagnosed, HAART na?ve HIV co-infection among children who were managed at a Tertiary Hospital in Ilorin, Nigeria. Result: Of the 60 HIV- infected children recruited, 11.7% had HIV co-infection with HBV or HCV. Children with co-infec- tions (mean age 8.43 ± 2.37 years) were significantly older than their HIV mono-infected counterparts (mean age 5.25 ± 3.96 years) (p = 0.011). There was no significant difference between HIV monoinfection and HIV co-infection with respect to gender (p = 0.758), ethnicity (p = 0.707), religion of parents (p = 0.436), family type (p = 0.184), social class (p = 0.535), previous transfusion (p = 0.053), scarification (p = 0.612), female genital mutilation (p = 0.778), and sharing of clippers (p = 0.806). The mean BMI, immunological staging (p = 0.535), baseline ALT (p = 0.940), and mean baseline CD4+ count (p = 0.928) were comparable. However, the body mass index of HIV co-infec- ted children decreased with age up till age 10 years. Conclusion: There were no risk factors, nor clinical features predictive of co-infection identified in this study. Co-infection did not negatively impact baseline, CD4+ count and ALT.

CD4^+ T cell-mediated presentation of non-infectious HIV-1 virion antigens to HIV-specific CD8^+ T cells

Background The mechanism of chronic immune activation and impairment of HIV-specific immune responses during chronic infection is not fully understood. However, it is known that high immune activation leads to more rapid progression to AIDS. We hypothesize that CD4^＋ T cell-mediated viral antigen presentation contributes to this pathologic immune activation in HIV-infected individuals. Methods HIV-specific T cells, responding to noninfectious HIV-1 virions as antigen, were measured by flow cytometric assays. These experimental conditions reflect the in vivo condition where noninfectious HIV-1 represents more than 99% of the antigens. Results CD4^＋ T cells purified from HIV-infected individuals were capable of cross presenting exogenous noninfectious HIV-1 virions to HIV-1-specific CD8^＋ T cells. Cross presentation required the entry of HIV-1 to CD4^＋ T cells and antigen translocation from endoplasmic reticulum to the Golgi complex. Blocking CD4^＋ mediated activation of HIV-specific CD8^＋ T cells and redirecting the viral antigens to antigen presenting cells improved HIV-specific T cell responses. Contusions One possible cause of chronic immune activation and impairment of HIV-1 specific T cell responses is represented by HIV-1 harboring CD4^＋ T cells cross presenting HIV-1 antigen to activate CD8^＋ T cells. This new mechanism provides the first evidence that cross presentation of noninfectious HIV-1 virions play a role in the immunopathogenesis of HIV-1 infection.

CD24 aggravates acute liver injury in autoimmune hepatitis by promoting IFN-γ production by CD4^(+) T cells

The T-cell-mediated immune response is implicated in many clinical hepatic injuries, such as autoimmune hepatitis and acute virus hepatitis. CD24 is widely expressed by different immune cells and plays an important role in the pathogenesis of many autoimmune diseases. However, the role of CD24 in T-cell-mediated liver injury has not been elucidated until now. Here we showed that CD24 deficiency protects mice from concanavalin A (ConA)-induced fulminant liver injury by reducing serum interferon-γ (IFN-γ) levels. CD24 expression by hepatic T cells was markedly increased following ConA challenge. Moreover, decreased IFN-γ production by hepatic CD4^(+) T cells in CD24-deficient mice was detected, which was correlated with downregulated phosphorylation of STAT1 in hepatic tissue. In vitro experiments also supported the conclusion that CD24 deficiency impaired IFN-γ production by CD4^(+) T cells following ConA, CD3/CD28 and phorbol myristate acetate/ionomycin stimulation. Our study suggests that CD24 deficiency confers hepatoprotection by decreasing CD4^(+) T-cell-dependent IFN-γ production in vivo, which suggests that CD24 might be a potential target molecule for reducing clinical hepatitis.

Cinnamon extract suppresses experimental colitis through modulation of antigen-presenting cells

AIM:To investigate the anti-inflammatory effects of cinnamon extract and elucidate its mechanisms for targeting the function of antigen presenting cells.METHODS:Cinnamon extract was used to treat murine macrophage cell line(Raw 264.7),mouse primary antigen-presenting cells(APCs,MHCII+) and CD11c+dendritic cells to analyze the effects of cinnamon extract on APC function.The mechanisms of action of cinnamon extract on APCs were investigated by analyzing cytokine production,and expression of MHC antigens and co-stimulatory molecules by quantitative real-time PCR and flow cytometry.In addition,the effect of cinnamon extract on antigen presentation capacity and APC-dependent T-cell differentiation were analyzed by [H3]-thymidine incorporation and cytokine analysis,respectively.To confirm the anti-inflammatory effects of cinnamon extract in vivo,cinnamon or PBS was orally administered to mice for 20 d followed by induction of experimental colitis with 2,4,6 trinitrobenzenesulfonic acid.The protective effects of cinnamon extract against experimental colitis were measured by checking clinical symptoms,histological analysis and cytokine expression prof iles in inflamed tissue.RESULTS:Treatment with cinnamon extract inhibited maturation of MHCII+ APCs or CD11c+ dendritic cells(DCs) by suppressing expression of co-stimulatory molecules(B7.1,B7.2,ICOS-L),MHCII and cyclooxygenase(COX)-2.Cinnamon extract induced regulatory DCs(rDCs) that produce low levels of pro-inflammatory cytokines [interleukin(IL)-1β,IL-6,IL-12,interferon(IFN)-γ and tumor necrosis factor(TNF)-α] while expressing high levels of immunoregulatory cytokines(IL-10 and transforming growth factor-β).In addition,rDCs generated by cinnamon extract inhibited APC-dependent T-cell proliferation,and converted CD4+ T cells into IL-10high CD4+ T cells.Furthermore,oral administration of cinnamon extract inhibited development and progression of intestinal colitis by inhibiting expression of COX-2 and pro-inflammatory cytokines(IL-1β,IFN-γ and TNF-α),while enhancing IL-10 levels.CONCLUSION:Our study suggests the potential of cinnamon extract as an anti-inflammatory agent by targeting the generation of regulatory APCs and IL-10+ regulatory T cells.

EXPRESSION CLONING OF A PROTECTIVE LEISHMANIA ANTIGEN

Parasite-specific CD8+ T cells have been shown to transfer protection against nLeishmania major in susceptible BALB/c mice.An epitope-tagged expression library was used to identify the antigen recognized by a protective CD8+ T cells clone. The expression library allowed recombinant proteins made in bacteria to be captured by macrophages for presentation to T cells restricted to major histompatibility complex class n. A conserved 36-kilodalton member of the tryptophanaspartic acid repeat family of proteins was identified that was expressed in both stages of the parasite life cycle. A 24-kilodalton portion of this antigen protected susceptible mice when administered as a vaccine with interleukin-12before injection.

急性胰腺炎早期患者IL-6,TNF,CD_4^+/CD_8^+的变化及意义

目的揭示重型胰腺炎发病机制和早期监测指标。方法对 12例重型胰腺炎 (SAP) ,15例轻型胰腺炎 (MAP)病人和 13例正常人 (N )的外周血用ELISA法测定IL -6及TNF ;用间接免疫荧光法测定CD4 +、CD8+细胞。结果SAP组IL-6水平明显高于MAP组及N组 (P <0 .0 1) ,但MAP组与N组比较无差异 (P >0 .0 5 )。IL -6大于 10 0 pg/ml时预测SAP的敏感性为83 .33 % ,特异性 93 .33 % ;三组间TNF检出率无差异 ;CD4 +百分率在SAP组明显下降 (P <0 .0 1)。SAP组IL -6与CD4 +百分率呈明显负相关 (r =-0 .6 196 ,P <0 .0 5 )。结论SAP早期IL -6升高和细胞免疫功能抑制可能属其早期反应 ,测定IL -6有助于轻。

乙型肝炎的T淋巴细胞亚群的演变规律

目的:了解不同类型乙型肝炎患者T淋巴细胞亚群的演变规律及意义。方法:我院2002年7月～2004年6月收治的16例急性肝炎、40例慢性肝炎及46例重型肝炎病例的抗凝血,通过流式细胞仪检测其T淋巴细胞亚群,对不同类型肝炎进行统计学分析。结果:慢性肝炎组与急性肝炎组比较CD3+,CD8+细胞计数降低且差异有显著性(P<0.05)。重型肝炎组与非重型肝炎组(急性肝炎组与慢性肝炎组)比较CD3+,CD4+,CD8+细胞计数明显降低(P<0.05),幼稚的CD4+,CD8+细胞计数明显升高(P<0.05)。结论:不同类型乙型肝炎的T淋巴细胞亚群有明显差异,乙型肝炎随着病情严重及病程延长,CD3+,CD4+,CD8+淋巴细胞逐渐减少,重型肝炎出现大量幼稚的CD4+CD8+淋巴细胞,T淋巴细胞亚群的变化可以反映病情严重程度及免疫状态,对免疫调节治疗有指导意义。

从HCV蛋白一级结构预测其C,E,NS5区的CD_4^+ T细胞抗原位点

我们根据ＣＤ４＋Ｔ细胞识别抗原位点的物理化学和生物学特征，设计了一个具有查找两亲性螺旋状结构（ａｍｐｈｉｐａｔｈｉｃｈｅｌｉｘｓｔｒｕｃｔｕｒｅ）肽段功能的计算机程序。用该程序对ＨＣＶ－１型病毒Ｃ、Ｅ（Ｅ１、Ｅ２／ＮＳ１）、ＮＳ５蛋白一级结构进行分析，发现这些蛋白区存在ＣＤ４＋Ｔ细胞识别位点。此结果支持了ＣＤ４＋Ｔ细胞对ＨＣＶＣ，Ｅ，ＮＳ５区可发生增殖反应的结论。提示该程序可作为一种预测ＣＤ４＋Ｔ细胞识别ＨＣＶ抗原位点的方法。

旋毛虫成虫可溶性抗原免疫小鼠T淋巴细胞亚群的动态变化

目的 观察旋毛虫成虫可溶性抗原免疫小鼠T淋巴细胞亚群的动态变化。方法采用流式细胞术分别检测旋毛虫感染后 7、14、2 1、2 8、35天小鼠外周血CD+ 4 、CD+ 8T淋巴细胞的百分率。结果 免疫小鼠CD+ 4 、CD+ 8细胞增加 ,CD+ 4 /CD+ 8细胞比值与正常组比较无明显差异。

间变性大细胞性T细胞性淋巴瘤中EB病毒检测及CD_(56)的表达

目的：研究间变性大细胞性Ｔ细胞性淋巴瘤（ａｎａｐｌａｓｔｉｃｌａｒｇｅＴｃｅｌｌｙｍｐｈｏｍａ，ＡＬＴＣＬ）ＥＢ病毒表达情况及其与ＣＤ５６阳性表达间的关系。方法：采用免疫组织化学ＬＳＡＢ法检测１５例ＡＬＴＣＬ中Ｋｉ１及ＣＤ５６的表达，并用原位杂交法检测其ＥＢＥＲｓ。结果：１５例ＡＬＴＣＬ中Ｋｉ１均阳性（１００％），５例ＣＤ５６阳性（３３３％），９例ＥＢＥＲｓ阳性。其中，３例ＡＬＴＣＬ中ＥＢＥＲｓ和ＣＤ５６共同阳性。结论：ＡＬＴＣＬ的发生同ＥＢ病毒感染有一定关系；部分ＡＬＴＣＬ中有ＣＤ５６阳性表达，ＥＢ病毒是否感染ＡＬＴＣＬ同ＣＤ５６表达无关。

Effects of“Moxibustion Serum”on Proliferation and Phenotypes of Tumor Infiltrating Lymphocytes

Tumor infiltrating lymphocytes (TIL) were cultured with “moxibustion serum”(MS), and the results were examined by flow cytometry. The results indicated that MS could enhance the proliferation of TIL,accelerate it to reach the exponential growth phase, and assist recombinant interleukin 2 (rIL-2) to enhance successively the percentage of CD3^+ positive cells, maintain the number of CD4^+ positive T cells, promote greatly the percentage of CD8^+ positive T cells among TILs, and reverse the CD4^+/CD8^+ ratio. Such cooperative effects rely on relative specificity of acupoints. It is suggested that MS is beneficial to the growth of TIL both in the aspects of proliferation and phenotypes.

EFFECTS OF ACUPUNCTURE ON THE IMMUNOLOGICAL FUNCTIONS IN HEPATITIS B VIRUS CARRIERS

A contrast study on the effects of manual acupuncture and electroacupuncture wasconducted in 60 cases of chronic hepatitis B carriers.The results demonstrated that theimmunological functions,both cellular and humoral,were markedly regulated asevidenced by the negative turnover rates of HBsAg,HBeAg,anti-HBc and HBcAg,as wellas the positive turnover rate of anti-HBe.

AIDS病毒与CD＋4靶细胞检测方法的研究

本文对ＡＩＤＳ病毒抗原及其靶细胞（ＣＤ＋４）检测方法的研究进展作了较系统的评述。深入分析了ｇｐ１２０、ＣＤ４受体分子与小肽的相互作用。

Role of LPS/CD14/TLR4-mediated inflammation in necrotizing enterocolitis:Pathogenesis and therapeutic implications

AIM:To establish the roles of lipopolysaccharide (LPS)/CD14/toll-like receptor 4 (TLR4)-mediated inflammation in a rat model of human necrotizing enterocolitis (NEC).METHODS: Six pairs of intestinal samples from human NEC were collected before and after recovery for histological and molecular analysis of inflammatory cytokines and signaling components. In the rat NEC model, we isolated 10-cm jejunum segments and divided them into six groups (n=6) for sham operation, treatment with LPS, bowel distension, combined bowel distension and LPS stimulation, and two therapeutic groups. The potential eff icacy of a recombinant CD18 peptide and a monoclonal CD14 antibody was evaluated in the latter two groups. The serum and tissue levels of several inflammatory mediators were quantified by real-time polymerase chain reaction, ELISA and immunoblotting.RESULTS: Human acute phase NEC tissues displayed significant increases (P<0.05) in levels of TLR4, CD14, myeloid differentiation protein (MD)-2, tumor necrosis factor (TNF)-α and nuclear factor-κB when compared to those after recovery. The histological and inflammatory picture of human NEC was reproduced in rats that were treated with combined bowel distension and LPS, but not in the sham-operated and other control rats. Serum levels of interleukin-6 and TNF-α were also elevated. The NEC pathology was attenuated by treating the NEC rats with a monoclonal CD14 antibody or an LPS-neutralizing peptide.CONCLUSION:LPS and distension are required to produce the histological and inflammatory features of NEC. A potential treatment option is blocking LPS activation and leukocyte infi ltration.

Association between polymorphisms in the Toll-like receptor 4,CD14,and CARD15/NOD2and inflammatory bowel disease in the Greek population

AIM: Crohn's disease(CD)and ulcerative colitis(UC)are multifactorial diseases with a significant genetic background.Apart from CARD15/NOD2 gene, evidence is accumulating that molecules related to the innate immune response such as CD14 or Toll-like receptor 4 (TLR4), are involved in their pathogenesis. In further exploring the genetic background of these diseases, we investigated the variations in the CARD15/NOD2 gene (Arg702Trp,Gly908Arg and Leu1007fsinsC), and polymorphisms in the TLR4 gene (Asp299Gly and Thr399Ile) as well as in the promoter of the CD14 gene (T/C at position -159) in Greek patients with CD and UC.METHODS: DNA was obtained from 120 patients with CD,85 with UC and 100 healthy individuals. Genotyping was performed by allele specific PCR or by PCR-RFLP analysis.RESULTS: The 299Gly allele frequency of the TLR4 gene and the T allele and TT genotype frequendes of the CD14 promoter were significantly higher in CD patients only compared to healthy individuals (P = 0.026＜0.05; P = 0.0048＜0.01 and P= 0.047＜0.05 respectively). Concerning the NOD2/CARD15mutations the overall presence in CD patients was significantly higher than that in UC patients or in controls.Additionally, 51.67% of the CD patients were carriers of a TLR4 and/or CD14 polymorphic allele and at least one variant of the NOD2/CARD15, compared to 27% of the UC patients. It should be pointed out that both frequencies significantly increased as compared with the 10% frequency of multiple carriers found in healthy controls. A possible interaction of the NOD2/CARD15 with TLR4 and especially CD14, increased the risk of developing inflammatory bowel disease (IBD).CONCLUSION: Our results indicate that co-existence of a mutation in either the TLR4 or CD14 gene, and in NOD2/CARD15is associated with an increased susceptibility to developing CD compared to UC, and to developing either CD or UC compared to healthy individuals.

Mobilization of hematopoietic progenitor cells in patients with liver cirrhosis

AIM:To test the hypothesis that liver cirrhosis is associated with mobilization of hematopoietic progenitor cells. METHODS:Peripheral blood samples from 72 patients with liver cirrhosis of varying etiology were analyzed by flow cytometry.Identified progenitor cell subsets were immunoselected and used for functional assays in vitro. Plasma levels of stromal cell-derived factor-1(SDF-1) were measured using an enzyme linked immunosorbent assay.RESULTS:Progenitor cells with a CD133 + /CD45 + CD14 + phenotype were observed in 61%of th patients.Between 1%and 26%of the peripheral bloo mononuclear cells(MNCs)displayed this phenotype Furthermore,a distinct population of c-kit + progenito cells(between 1%and 38%of the MNCs)could b detected in 91%of the patients.Additionally,18% of the patients showed a population of progenito cells(between 1%and 68%of the MNCs)that wa characterized by expression of breast cancer resistanc protein-1.Further phenotypic analysis disclosed tha the circulating precursors expressed CXC chemokin receptor 4,the receptor for SDF-1.In line with thi finding,elevated plasma levels of SDF-1 were presen in all patients and were found to correlate with th number of mobilized CD133 + progenitor cells.

条件培养液对脐血CD_(34)^+细胞扩增效应的实验研究

目的探讨并分析不同条件培养液对脐血CD+ 34 细胞的体外扩增效应及影响因素。方法利用 4种条件培养液 (胎儿肌肉、胎盘组织、外周血、脐血单个核细胞 )对脐血CD+ 34 细胞进行 2周的体外扩增 ,并和三细胞因子组合 :干细胞因子 (stemcellfactor ,SCF)、血小板生成素 (thrombopoietin ,TPO)、flt 3配基 (flt 3ligand ,FL) ,对脐血CD+ 3 4 细胞扩增结果进行了比较 ;利用ELISA方法检测 4种条件培养液中细胞因子 [白细胞介素 1(interleukin 1,IL 1)、白细胞介素 6 (interleukin 6 ,IL 6 )、FL、TPO]的浓度。结果脐血单个核细胞条件培养液及细胞因子组合对脐血CD+ 3 4 细胞均有明显的扩增效应 ,脐血组优于细胞因子组合 ;4种条件培养液中 ,脐血组细胞因子FL的含量明显高于其余条件培养液组。结论脐血条件培养液可作为体外培养扩增脐血CD+ 34 细胞有效而廉价的扩增剂 ;细胞因子FL可能是造成不同条件培养液对脐血CD+ 34