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Haiming Wei

Publications and source records attributed to Haiming Wei.

At least 37 records · Page 2Linked to original sources
PubMed2005

Opposing effect of IFNgamma and IFNalpha on expression of NKG2 receptors: negative regulation of IFNgamma on NK cells.

The effector functions of natural killer (NK) cells are regulated by integrated signals across an array of stimulatory and inhibitory receptors interacting with target cell surface ligands. The regulatory effect of interferon-alpha (IFNalpha) and interferon-gamma (IFNgamma) on expression of the family of NKG2 receptors, stimulatory NKG2D receptor and inhibitory NKG2A receptor, and cytolysis of the target tumor cells (MICA+ and HLA-E+) were studied. Results show that IFNgamma and IFNalpha influence NK cell function differently. Interferon-alpha stimulates expression of stimulatory NKG2D receptors and inhibits the expression of inhibitory NKG2A receptors on NK cells. Contrary to the stimulatory effect of IFNalpha, IFNgamma inhibits cytolysis by NK cells of tumor cells expressing MICA or HLA-E cell surface proteins. Blocking NKG2D or NKG2A receptor activity with monoclonal antibodies partly attenuates the inhibitory effect of IFNgamma while promoting the effects of IFNalpha on NK cytolysis. These results show for the first time that IFNgamma negatively regulates NK cells through NKG2 receptors, and that the balance between stimulatory and inhibitory signals through the NKG2 family of receptors may be controlled by two opposing interferons. Modulating the balance between stimulatory and inhibitory signals through cell surface receptors on NK cells may open a new approach to NK cell-based biotherapy for cancer and infectious diseases.

Antibodies, Monoclonal↗
PubMed2005

Involvement of human natural killer cells in asthma pathogenesis: natural killer 2 cells in type 2 cytokine predominance.

BACKGROUND: T H 2 cells play a pivotal role in the pathogenesis of human asthma. Natural killer (NK) cells are also thought to divide into NK1 and NK2 subsets. OBJECTIVE: Whether NK1 or NK2 cells are involved in asthma remains unclear. METHODS: Triple-color flow cytometry for detecting intracellular cytokine and NK cell surface phenotype from asthmatic patients was used. The NK cell cloning and analysis with RT-PCR for cytokine expression and Western blotting for signal transducer and activator of transcription activation were performed. RESULTS: For the first time, we observed that the ratio of IL-4 + CD56 + NK2 cells in PBMCs of 8 asthmatic patients were higher than in healthy individuals. NK cell clones were then obtained by means of limited dilution, and the average mean of the relative intensity of PCR products for type 2 cytokines significantly increased in the asthmatic patients. Signal transducer and activator of transcription 6, a key transcript factor of type 2 phenotype, was constitutively activated in NK2 clones from asthmatic patients. We cocultured freshly purified NK cells from asthmatic patients with IFN-gamma and anti-IL-4 antibody in the presence of IL-15 and found that the content of IL-4 + NK2 cells significantly decreased after treatment. Interestingly, NK2-biased status in asthmatic patients was reversed when patients recovered from regular therapy. CONCLUSION: The results suggest that the NK2 cell subset is involved in the pathogenesis of asthma.

Adolescent↗
PubMed2005

The inhibitory effects of synthetic short peptides, mimicking MICA and targeting at NKG2D receptors, on function of NK cells.

NKG2D is an activating receptor expressed on most of human NK cells, one of whose ligands is MICA. Based on the crystal structure of NKG2D-MICA complex, we synthesized three short peptides (P1, P2 and P3), mimicking functional alpha1 and alpha2 domain of MICA. The inhibitory effects of three peptides on NK-92 cells, a human NK cell line against Hela cells were observed and the inhibitory percentage was 38% at maximum for P1+P2+P3 in concentration of 1nM. The same peptides had no effect on NK-92 cell against target cells lacking MICA (K562 cells line). The unrelated peptides as controls had no effect on the system. Two peptides (P2 and P3) were prolonged at one or both ends, and the longer forms of peptides exerted stronger inhibitory effects than their shorter forms. Each combination of two peptides exerted a stronger function than single peptide (P1, P2, P3), indicating that shedding of longer amino acid sequence of alpha1 domain or more domain sites of MICA are better than shorter sequence and fewer sites. P1+P2+P3 revealed the almost same inhibitory rate as the soluble MICA (sMICA). P1+P2+P3 were also able to alleviate the concanavalin A-induced murine autoimmune hepatitis in vivo, conforming the similarity of NKG2D between human and mice. The results demonstrate that MICA-mimicking peptides will be useful to search the specific functional sites for NKG2D-MICA interaction, but also promising in explaining NKG2D-related autoimmunity.

Alanine Transaminase↗
PubMed2005

Impaired NK cell cytotoxicity by high level of interferon-gamma in concanavalin A-induced hepatitis.

Unlike T cells, the role of natural killer (NK) cells is not well documented in the concanavalin (ConA)- induced hepatitis model. This study aimed to investigate the regulatory effect of high levels of interferon-gamma (IFN-gamma) on NK cells in ConA-induced hepatitis. The cytotoxicities of NK cells from ConA-injected mice or NK cell lines (NK92 and NKL) were detected by the 4-h 51Cr release assay. Depletion of NK cells with AsGM1 antibody was used to assess the NK cell role in ConA-induced hepatitis. Expression of NK cell receptors and cytotoxic molecules was measured by reverse transcription-polymerase chain reaction. Twelve hours after ConA injection, serum IFN-gamma was significantly increased in wild mice, but not in severe combined immunodeficiency mice, and hepatic NK cells exerted impaired cytotoxicity against YAC-l cells in wild mice. Eight hours after NK cells were incubated in serum from ConA-treated mice, NK cell cytotoxicity was down-modulated and the effect was abolished by pretreatment with neutralizing serum IFN-gamma with specific antibody in vitro. A high concentration of IFN-gamma (> 1000 U/mL) inhibited the cytotoxicities of 2 NK cell lines in vitro, accompanied with down-regulation of NKG2D transcripts and up-regulation of NKG2A/B and KIR2DL transcripts. The inhibitive role of IFN-gamma was not seen in NKG2D ligand negative cells. These results suggest that NK cell cytotoxicity was inhibited by high levels of IFN-gamma in ConA-induced hepatitis, which may relate to the dispensable role of NK cells.

Alanine Transaminase↗
PubMed2005

Field evaluation of a rapid, visually-read colloidal dye immunofiltration assay for Schistosoma japonicum for screening in areas of low transmission.

OBJECTIVE: To determine the validity of a recently developed rapid test--a colloidal dye immunofiltration assay (CDIFA)--used by health workers in field settings to identify villagers infected with Schistosoma japonicum. METHODS: Health workers in the field used CDIFA to test samples from 1553 villagers in two areas of low endemicity and an area where S. japonicum was not endemic in Anhui, China. All the samples were then tested in the laboratory by laboratory staff using a standard parasitological method (Kato-Katz), an indirect haemagglutination assay (IHA), and CDIFA. The results of CDIFA performed by health workers were compared with those obtained by Kato-Katz and IHA. FINDINGS: Concordance between the results of CDIFA performed in field settings and in the laboratory was high (kappa index, 0.95; 95% confidence interval, 0.93-0.97). When Kato-Katz was used as the reference test, the overall sensitivity and specificity of CDIFA were 98.5% and 83.6%, respectively in the two villages in areas of low endemicity, while the specificity was 99.8% in the nonendemic village. Compared with IHA, the overall specificity and sensitivity of CDIFA were greater than 99% and 96%, respectively. With the combination of Kato-Katz and IHA as the reference standard, CDIFA had a sensitivity of 95.8% and a specificity of 99.5%, and an accuracy of 98.6% in the two areas of low endemicity. CONCLUSION: CDIFA is a specific, sensitive, and reliable test that can be used for rapid screening for schistosomiasis by health workers in field settings.

Animals↗
PubMed2005

Antisense-induced blockade of GATA-3 expression could inhibit Th2 excursion of tumor cells in vitro and in vivo.

Previous studies have shown that tumor cells predominantly express Th2 type cytokines and transcription factors. GATA-3, as a Th2-specific transcription factor, plays a central role in positive-regulating Th2 development. So whether the expression of GATA-3 in tumor cells has any effect on tumor development is a question of interest. In the present study, we inhibited the expression of GATA-3 in tumor cells through antisense RNA blockade technique, and observed its effects on tumor in vitro and in vivo. Our results showed that antisense GATA-3 treatment could inhibit the expression of TNF-alpha and Th2 cytokines in tumor cells, and antisense-induced blockade of GATA-3 could also depress tumor growth in tumor-bearing mice. We suggest that the ratio of T-bet/GATA-3 can be evaluated as a more important marker of the status of Th1/Th2 type. And our results might provide some evidence about the molecular regulatory mechanisms in tumor cell development.

Animals↗
PubMed2005

Isolation of lymphocytes and their innate immune characterizations from liver, intestine, lung and uterus.

In steady-state conditions, the number and distribution of lymphocyte populations are under homeostatic control. New lymphocytes are continuously produced in primary and secondary lymphoid organs and then achieve immune-competence within different tissues, and they must challenge with resident cells for survival. The first step in the study of tissue lymphoid cells is their isolation in intact and viable form appropriate for establishment of in vitro culture systems. For reasons of simplicity, cell purity, cell yields and various purposes, lymphocytes obtained from different tissues in different labs were subjected to diverse protocols. To fully elucidate the nature of the local immune system as well as to adequately study the innate role of lymphocytes in liver, intestine, lung and uterus, we briefly reviewed the characterization of resident lymphocytes, and additional information on those cells from non-lymphoid tissues by using the recommended operation procedure was also presented.

Animals↗
PubMed2004

Tumor-induced suppression of interferon-gamma production and enhancement of interleukin-10 production by natural killer (NK) cells: paralleled to CD4+ T cells.

The predominance of type two cytokines in syngeneic B16 tumor-bearing mice was confirmed by analysing supernatant contents and mRNA copies of IFN-gamma, IL-4, IL-5, IL-10 and IL-13 from splenocytes. The cytokine-producing lymphocytes were then examined by double-staining flowcytometry. Both CD4+IFN-gamma+ T cells and DX5+IFN-gamma+ NK cells from spleen significantly declined, interestingly, the declining degrees of DX5+IFN-gamma+ NK cells were much greater than those of CD4+IFN-gamma+ T cells by the percentage in whole NK or T cells or the absolute amounts per spleen at early tumor stage (day 10) or tumor-advanced stage (day 20). In contrast to DX5+IFN-gamma+ NK cells, DX5+IL-10+ NK cells increased during tumor progression, the increasing degrees of DX5+IL-10+ NK cells were also much greater than those of CD4+IL-10+ T cells by the percentage or the absolute amounts. Though the percentage of DX5+IL-4+ NK cells only increased in early tumor stage (day 10), the increasing degree was also greater than that of CD4+IL-4+ T cells. In 20xfield view under laser confocal microscope, the mean numbers of DX5+IFN-gamma+ NK cells and CD4+IFN-gamma+ T cells dramatically declined after tumor inoculation. These results suggest that cytokines produced by NK cells, at least partly, account for the balance of type one and two cytokines as done by T cells, and in some conditions, that the NK1 or NK2 cells were possibly more sensitive to tumor progression.

Animals↗
PubMed2004

A balanced expression of two chains of heterodimer protein, the human interleukin-12, improves high-level expression of the protein in CHO cells.

Interleukin-12 (IL-12) comprises of p40 and p35 subunits that are encoded by genes on separate chromosomes and form p70 heterodimer, a bioactive protein, and free p40, an antagonist of IL-12. Balance expression of two subunits within cells would be the key for high-level of production of bioactive IL-12. Thinking about different expression efficiencies of two genes (p40 gene with higher efficiency), we selected two expression vectors with different efficiencies and inserted genes of p40 and p35 into them separately and co-transfected them into Chinese hamster ovary (CHO) cells. The high-level expression of IL-12 was obtained when p40 cDNA was inserted into pcDNA3 (lower expression vector) and p35 cDNA was inserted into pEE14 (higher expression vector), but using pEE14 for p40 cDNA and pcDNA3 for p35 cDNA, which was opposite to the optimal design, or pEE14 or pcDNA3 for both p35 cDNA and p40 cDNA did not obtain high-level of production of p70 heterodimer, the bioactive IL-12. We also observed that using two chemical reagents in combination, as a pressure selection method or amplification for the two vectors, markedly enhanced the IL-12 production, when compared with any one selection chemical. Our results indicated that the balance expressions of two chains of hetrodimer protein, such as p40 and p35 of IL-12, would be a better choice to obtain high-level of production of the proteins.

Animals↗
PubMed2004

Involvement of natural killer cells in PolyI:C-induced liver injury.

BACKGROUND/AIMS: The roles of T cells, natural killer T cells (NKT) and macrophages in autoimmune hepatitis have been well documented. However, the roles of natural killer (NK) cells in liver injury remain obscure. Here we examined the effect of Polyinosinic: polycytidylic acid (PolyI:C)-activated NK cells on liver injury. METHODS: Mice were intraperitoneally injected with PolyI:C at a dose of 20mug/g body wt. The percentage and absolute number of NK cells in the liver were analyzed with flow cytometry. Serum alanine transaminase (ALT) and aspartate aminotransferase (AST) assay and H-E staining were used to evaluate the liver injury. RESULTS: Following PolyI:C injection, NK cells accumulation and activation occurred in the liver. Meanwhile, slight elevation of ALT/AST in the serum, mild inflammation and focal necrosis in the liver were also observed. Depletion of NK cells markedly attenuated PolyI:C-induced liver injury. Neutralization of endogenous Interleukin-12 produced by Kupffer cells abrogated the accumulation of NK cells in the liver and subsequent liver injury. The liver injury was also alleviated by neutralization of vascular cell adhesive molecule-1. CONCLUSIONS: These findings suggest that PolyI:C preferentially recruits and activates hepatic NK cells, which may be responsible for the mild hepatitis.

Alanine Transaminase↗
PubMed2004

Characterization of interleukin-15 gene-modified human natural killer cells: implications for adoptive cellular immunotherapy.

BACKGROUND AND OBJECTIVES: Natural killer (NK)-92 cells are effective against a broad range of malignant targets both in vitro and in vivo. Interleukin-15 (IL-15) is an important cytokine for NK cell development and differentiation. IL-15 gene-modified NK-92 cells need to be characterized and their clinical implications investigated. DESIGN AND METHODS: IL-15 cDNA was inserted into a pcDNA3 eukaryotic expression vector and the recombinant vector (pcDNA3-IL15) was tranfected into NK-92 cells. The IL-15 gene-modified NK-92 cells (NK92-IL15) were cloned and characterized with regard to their cytokine production, proliferation, cytotoxicity and surface phenotype. RESULTS: NK92-IL15 cells continuously produced a high level of IL-15 in culture supernatant, which made the cells proliferate significantly more rapidly in response to stimulation with low doses of IL-2 or IL-15; the cumulative number of cells in long-term culture was also significantly higher. NK92-IL15 cells became adherent to plastic and their expression of CD54 increased, which may explain their improved proliferating potential, like adherent NK cells. NK92-IL15 cells were more strongly cytotox against a broad range of target tumor cells than the parent NK-92 cells, and this increased cytotoxicity was correlated to the increased expression of cytotoxic effector molecules, such as perforin, Fas ligand and IFNgamma, and up- or down-regulated expression of activating or inhibitory NK cell receptors (NKG2D or NKG2A/CD94). INTERPRETATION AND CONCLUSIONS: These results demonstrate that NK92-IL15 cells are promising for adoptive cellular immunotherapy.

Cell Line↗
PubMed2004

Characterization of stem cell factor gene-modified human natural killer cell line, NK-92 cells: implication in NK cell-based adoptive cellular immunotherapy.

NK-92 cells are effective against a broad range of malignant targets both in vitro and in vivo. Stem cell factor (SCF) is an important early acting cytokine for NK cell development. The characterization and implication in clinic of SCF gene-modified NK-92 cells need to be investigated. SCF cDNA was inserted into pcDNA3 eukaryotic expression vector and the recombinant vector (pcDNA3-SCF) was transfected into NK-92 cells. The SCF gene-modified NK-92 cells (NK92-SCF) were cloned and characterized by cytokine gene expression, proliferation potential, cytotoxic function and surface phenotype. NK92-SCF cells continuously produced a high level of SCF in culture supernatant, which made the cells proliferate significantly more rapidly in response to IL-2 or IL-15 stimulation, the cumulative amount of cells in long-term culture was significantly higher. NK92-SCF cells exerted stronger cytotoxicity against a broad range of target tumor cells than their parent NK-92 cells, which was correlated to the increased expression of cytotoxic effector molecules such as perforin and Fas ligand. NK92-SCF cells became more heterogeneous; the CD56(High) and CD56(Low) subsets appeared, which may, at least partly, explain the increased proliferating and cytotoxic potential of NK92-SCF cells. SCF gene-modified NK-92 cells (NK92-SCF cells) are more promising than their parent cells for adoptive cellular immunotherapy.

Cell Division↗
PubMed2004

Type two cytokines predominance of human lung cancer and its reverse by traditional Chinese medicine TTMP.

Type 2 cytokines are usually predominant in tumor patients and associated with tumor progression. To explore whether reversing of type 2 predominance could be a promising strategy in tumor immunotherapy, PBMC of 35 lung cancer patients and 19 healthy subjects were prepared and subjected to be examined for cytokine secretion and gene expression. Tetra-Methylpyrazine (TTMP), extracted from a traditional Chinese medicinal herb which has been used in clinic to reverse the Th2 status of cancer patients in China, was added to PBMC culture. Determined by RT-PCR, the positive percentages of mRNA expression of type 1 cytokines (8.6% for IFN-gamma and 11.4% for IL-2) were lower than those of type 2 cytokines (71.4% for IL-4, 60% for IL-6 and 80% for IL-10) in patients' PBMCs. The potential of gene expressing (measured as relative intensity to the ratio of beta-actin) in the patients for type 1 cytokines was also in a low level (0.111 for IFN-gamma, 0.119 for IL-2) in comparison with a relative high level for type 2 cytokines (0.319 for IL-4, 0.303 for IL-6 and 0.377 for IL-10). Meanwhile, both positive percentage and relative intensity of gene expression were lower for a type 1 cytokine-related transcription factor T-bet (31.4% and 0.142, respectively) than those for type 2 cytokine-related GATA3 (85.7% and 0.378, respectively). The blood serum levels of IFN-gamma and IL-2 in the patients were slightly lower but not significantly when compared with healthy control. In contrast, the levels IL-4 and IL-6 in patients were significantly higher than those in healthy subjects by ELISA analysis. TTMP could enhance supernatant concentration and gene expression levels of IFN-gamma, IL-2 and T-bet, but reduce those of type 2 cytokines. These results demonstrate that the lung cancer patients had a predominant expression of type 2 cytokines and TTMP could reverse the type 2 dominant status, which might offer an alternative therapeutic regime for lung cancer patients.

Adult↗
PubMed2004

The role of innate immune cells in the response of heat-treated Mycobacterium tuberculosis (M.tb) antigens stimulating PBMCs.

The proliferation response of gammadelta T cells to the antigen from heat-treated Mycobacterium tuberculosis H37Ra (M.tb Ag) was used as a good model in gammadeltaT cell research. From preliminary research it is found that activated NK cells positively elevated gammadeltaT cells proliferation after simulating PBMCs with M.tb Ag. To investigate different behaviors of NK cells, gammadeltaNKT cells, gammadeltaT cells and relationships between these cell subsets, activation and proliferation of different cell subsets of PBMCs in response to M.tb Ag were analyzed. We demonstrated that NK cells, gammadeltaNKT cells and gammadeltaT cells could be activated after stimulation with M.tb Ag. gammadeltaNKT cells and gammadelta T cells proliferated while the number of NK cells decreased after 11 day-simulation with M.tb Ag. Meanwhile, at the early time of stimulation the cytotoxicity of PBMCs was enhanced.

Antigens, Bacterial↗
PubMed2003

IFNalpha regulates NK cell cytotoxicity through STAT1 pathway.

Human natural killer (NK) cell lines (YT and NK-92) and freshly isolated human NK cells were used to determine signal pathway (s) and their cytolysis-related molecules involved in IFNalpha-stimulated natural cytotoxicity. NK cells displayed apparently augmented cytotoxicity against target tumor cells (K562) and up-regulated gene expression of cytolytic effectors Fas-L and perforin in response to IFNalpha stimulation. Meanwhile, the tyrosine phosphorylation of STAT1 of NK cells was quickly induced, but other pathways including STAT3, STAT6, ERK1/2, p38 MAPK, JNK/SAPK, PI-3K, NF-kappaB were not or only weakly activated. Transient expression of dominant-negative form of STAT1 (DN STAT1) markedly inhibited STAT1 activation and then alleviated cytolysis activity of IFNalpha-treated YT cells, which was correlated to a markedly down-regulated expression of IRF-1, a key transcription factor necessary for cytotoxicity of IFNalpha/beta-activated NK cells. The results indicate that STAT1 activation play a crucial role in IFNalpha signaling for cytolysis function of NK cells.

Cell Division↗
PubMed2003

Use of interleukin-15 for preparation of adherent NK cells from human peripheral blood: comparison with interleukin-2.

To search the possibility of utilizing interleukin-15 (IL-15) in preparation of adherent human natural killer (A-NK) cells, recombinant human IL-15 (rhIL-15) or rhIL-2 (500 u/ml of each cytokine) were added to purified human NK cell culture in 24-well plastic plate. The cytokine-induced adherent ratio was calculated by percentage of A-NK cell in whole NK cells. The cytotoxicity of NK cells (NA- or A-NK cells) was examined by 4-h 51Chromium release assay, the surface markers of NK cells were checked by flow cytometry, and the cytokines were analyzed by reverse transcript (RT)-PCR and ELISA method. RhIL-15-induced adherence of human NK cells into plastic was higher than IL-2 when harvesting the A-NK cells at each hour point from hr 1 to hr 12. IL-15- and IL-2-induced adherent ratio peaked to 36.67% and 27.73% at hr 1, and the IL-15-induced adherent ratio was around two folds higher than IL-2-induced group at hrs 2, 3, 4, 5, 6, 7, and 8. The IL-15 group expanded more rapidly than IL-2 during 2 weeks' culture. IL-15- and IL-2-A-NK cells exerted similar levels of higher cytotoxic potentials. A-NK cells were characterized with phenotypes of CD3(-)CD16(+)CD56(+) (more than 93%) in the presence of IL-2 or IL-15 stimulation. CD54, an intracellular adhesion molecule (ICAM), was also continuously expressed in A-NK cells (more than 85%) induced by each cytokine. Interestingly, IL-15 stimulated relatively low level of expression of CD18, a beta2 integrin molecule related to lymphocyte apoptosis in A-NK cells (11.45%), whereas IL-2 exerted a strong effect on CD18 expression (87.54%). IL-11b was only expressed at A-NK cell induced by IL-2 (49.56%), IL-15 did not exert any stimulating effect on CD11b expression. All A-NK cells expressed high levels of interferon gamma (IFNgamma) after stimulation with IL-2 or IL-15. In contrast to IL-2, IL-15 did not stimulate gene expressions of type 2 cytokines (e.g. IL-4, IL-6, IL-10 and IL-13) in A-NK cells. The results indicate that rhIL15 is possibly a stronger stimulator for A-NK cell preparation by improving adherence and proliferation through inhibiting apoptosis by down-regulating the expression of CD18 and type 2 cytokines.

Biomarkers↗
PubMed2003

The effects of natural killer-cell depletion on ex vivo expansion of hematopoietic progenitor cells from umbilical cord blood.

BACKGROUND AND OBJECTIVES: The small total number of hematopoietic progenitor cells (HPC) in cord blood limited its use in adult recipients. Since the hematopoiesis might be controlled by both positive and negative factors, the finding of negative cellular components and thereafter depletion of them would be of importance for further expansion of HPC from cord blood in vitro. The role of natural killer cells (NK cells) in hematopoiesis remains unclear and needs to be elucidated. DESIGN AND METHODS: Cord blood mononuclear cells were co-cultured in a liquid culture system containing the hematopoietic cytokines interleukin (IL)-1, IL-3, IL-6, stem cell factor (SCF), granulocyte-monocyte colony-stimulating factor (GM-CSF) and G-CSF for a total of 20 days with or without depletion of NK cells. RESULTS: The percentage of CD34+ cells was significantly higher in the NK-cell-depleted group at each time point (day 5, day 10, day 15, day 20). This finding was further confirmed by examination of functional HPC including CFU-GM and CFU-GEMM. The intracellular interferon (IFN)-gamma and tumor necrosis factor (TNF)-alpha content of CD56+ NK cells increased more than 10-fold after incubation with hematopoietic cytokines (day 4, day 8). Neutralization of IFNgamma or TNFalpha, present in liquid culture, also significantly increased CFU-GM formation and CD34+ cell content. INTERPRETATION AND CONCLUSIONS: The results indicate that depletion of NK cells may be beneficial in producing hematopoietic progenitor cells from cord blood in ex vivo expansion systems. The effect of NK-cell depletion on ex vivo expansion of hematopoietic stem cells should be further assessed by a repopulating cell assay in NOD/SCID mice.

Antigens, CD34↗