Biomedical subjects

Ying Liu

Publications and source records attributed to Ying Liu.

At least 397 records · Page 22Linked to original sources

PubMed2003

[Eukaryotic expression and application of human CD226 Ig fusion protein containing 3C protease-restricted site].

AIM: To construct, express and characterize the eukaryotic expression vector of encoding human CD226 (PTA1) extracellular region Ig fusion protein gene containing 3C protease-restricted site. METHODS: The gene fragment encoding extracellular region of human CD226 was cloned into the eukaryotic expression vector p-3C-Ig containing 3C protease-restricted site and human Ig Fc fragment gene. After sequencing, the vector was transfected into COS7 cells, and the expressed molecule was purified by affinity chromatography. Finally, the product was characterized by immunofluorescent staining and 3C protease digestion. RESULTS: After expression and purification, the Ig fusion protein could bind effectively to the CD226 ligand expressed on ECV304 cells. The Fc fragment could also be cut off by 3C protease, so that the CD226 extracellular fragment was obtained. CONCLUSION: The extracellular region of human CD226 Ig fusion protein with 3C protease-restricted site is expressed successfully in COS-7 cells, which lays the foundation for the structural and functional study of this molecule.

Animals↗

PubMed2003

[Cloning of a DnaJ homolog chaperon PBP and its subcellular localization].

AIM: To isolate and identify a human DnaJ homolog chaperon, PBP, from a human skeleton cDNA library, and to analyze its expression and distribution in transfected mammalian cells. METHODS: (32)p-dCTP labeled probe hybridization was used to screen the human skeleton cDNA library and sequence of the positive clones were analyzed. Then PBP gene was transfected into COS-7 cells using lipofectamin. PBP expressed in the cells were detected by Western-blot and indirect immunofluorescence staining. RESULTS: A full-length(1.5 kb) cDNA of peripherin-binding protein (PBP) was identified, which is identical with that of mrj. Full length PBP was mainly localized to cytoplasms of COS-7 cells in interphase, and to nuclei in mitosis. CONCLUSION: The results indicate that besides cooperating with DnaK (HSP70), PBP itself plays an important role as a member of DnaJ family. PBP may also be involved in the regulation of cell cycle.

Amino Acid Sequence↗

PubMed2003

[Preparation and characterization of monoclonal antibodies against rat Nogo molecule].

AIM: To prepare monoclonal antibodies against rat Nogo molecule and study the distribution of Nogo in rat central nervous system (CNS). METHODS: Murine mAbs were prepared by hybridoma technique. The distribution of Nogo in rat CNS was identified by immunofluorescent histochemical staining. RESULTS: Three hybridoma cell lines, FMU-Nogo1, FMU-Nogo2 and FMU-Nogo3, secreting mAbs against rat Nogo molecule were obtained. The titers of ascitic mAbs reached to 10(-6) and the Ig subclass of FMU-Nogo1, FMU-Nogo2 and FMU-Nogo3 was IgG2b(kappa), IgG1(kappa) and IgG1(kappa), respectively. Moreover, these mAbs could be used in immunofluoresent histochemical staining. The results showed that rat Nogo molecule could be detected in Purkinje cell layer and granual layer of rat cerebellum and on oligodendrocyte in white matter of rat spinal cord.Furthermore, these mAbs could be used in Western blot for detecting Nogo molecule present in rat spinal cord. CONCLUSION: Three mAbs against rat Nogo molecule were successfully prepared, which can provide a useful tool in research on the structure and functions of Nogo molecule in CNS.

Animals↗

PubMed2003

[Expression of phosphofructokinase gene from Escherichia coli K-12 in obligately autotrophic bacterium Acidithiobacillus thiooxidans].

A plasmid pSDK-1 containing the Escherichia coli phosphofructokinase-1 (EC 2.7.1. 11) gene (pfkA) was constructed and transferred into Acidithiobacillus thiooxidans Tt-Z2 by conjugation. The transfer frequency of plasmid from E. coli to Tt-Z2 was 2.6 x 10(-6). More than 68% of Tt-Z2 cells carried the recombinant plasmids after being cultured for 50 generations without selective pressure, which showed that pSDK-1 was maintained consistently in Tt-Z2. The pfkA gene from E. coli could be expressed in this obligately autotrophic bacterium but the enzyme activity (14 U/g was lower than that in E. coli (K-12: 86 U/g; DF1010 carrying plasmid pSDK-1: 97 U/g). In th presence of glucose, the Tt-Z2 transconjugant consumed glucose leading to a better growth yield.

Acidithiobacillus thiooxidans↗

PubMed2002

Super/subcritical fluid chromatography chiral separations with macrocyclic glycopeptide stationary phases.

The chiral recognition capabilities of three macrocyclic glycopeptide chiral selectors, namely teicoplanin (Chirobiotic T), its aglycone (Chirobiotic TAG) and ristocetin (Chirobiotic R), were evaluated with supercritical and subcritical fluid mobile phases. A set of 111 chiral compounds including heterocycles, analgesics (nonsteroidal antiinflamatory compounds), beta-blockers, sulfoxides, N-protected amino acids and native amino acids was separated on the three chiral stationary phases (CSPs). All separations were done with an outlet pressure regulated at 100 bar, 31 degrees C and at 4 ml/min. Various amounts of methanol ranging from 7 to 67% (v/v) were added to the carbon dioxide along with small amounts (0.1 to 0.5%, v/v) of triethylamine and/or trifluoroacetic acid. The Chirobiotic TAG CSP was the most effective closely followed by the Chirobiotic T column. Both columns were able to separate, partially or fully, 92% of the enantiomers of the compound set. The ristocetin chiral selector could partially or baseline resolve only 60% of the enantiomers tested. All separations were done in less than 15 min and 70% were done in less than 4 min. The speed of the separations is the main advantage of the use of SFC compared to normal-phase HPLC. In addition, SFC is advantageous for preparative separations with easy solute recovery and solvent disposal.

Chromatography, Liquid↗

PubMed2002

Regulation of BRCA1 phosphorylation by interaction with protein phosphatase 1alpha.

Numerous reports have revealed that the tumor suppressor BRCA1 may play an important role in DNA damage repair. BRCA1 is expressed and phosphorylated during cell cycle progression and after DNA damage. BRCA1 is hypophosphorylated in G0-G1 and probably during mitosis as well. Kinases known to phosphorylate BRCA1 include cyclin-dependent kinase 2, as well as ataxia telangiectasia-mutated (ATM) and ATM and Rad3-related kinase (ATR), which function in G2 checkpoint control. However, protein phosphatases responsible for dephosphorylation of BRCA1 had yet to be identified. hCds1, which acts downstream of ATM, also phosphorylates a BRCA1 fragment containing amino acids 759-1064 [BRCA1 fragment 4 (BF4)]. We have used a GST-BF4 protein phosphorylated by hCds1 [glutathione S-transferase (GST)-BF4-P] as a substrate to identify potential phosphatases responsible for BRCA1 dephosphorylation. Data presented here show that both recombinant protein phosphatase 1 alpha (PP1alpha) catalytic subunit and endogenous PP1alpha dephosphorylate GST-BF4-P. Inhibitor 2 abolishes this activity. Overexpression of PP1alpha partially inhibits hyperphosphorylation of BRCA1 after ionizing radiation, indicating that PP1alpha dephosphorylates BRCA1 in vivo. BRCA1 and PP1alpha reciprocally coimmunoprecipitate, and a glutathione S-transferase pull-down assay shows that PP1alpha catalytic subunit associates directly with the BF4 region of BRCA1. In addition, BRCA1 inhibits PP1alpha activity. Therefore, BRCA1 is both a substrate and a regulator of PP1alpha. The interaction between BRCA1 and PP1alpha thus may play a role in DNA damage repair and cell cycle progression.

Animals↗

PubMed2002

Fluorescence assay based on preconcentration by a self-ordered ring using berberine as a model analyte.

A novel assay for trace amounts of fluorescent analytes is proposed based on the assembly of a self-ordered ring (SOR) through capillary flow in a sessile droplet on a glass slide support. After solvent evaporation of the sessile droplet containing a fluorescent analyte on a hydrophobic-treated glass slide, an outward capillary flow of the solvent from the interior of the droplet occurs. The resultant outward capillary flow then carries the analyte to the perimeter of the droplet spot where the analyte deposits and forms a fluorescent SOR. For the model analyte of berberine, SORs with outer diameter less than 1.2 mm and ring belt width less than 19 microm can be obtained depending on the droplet volume of the berberine solution. Data analysis for the digitally imaged SOR by using a CCD camera showed that the berberine molecules across the SOR belt section follow a Gaussian distribution, and the maximum fluorescent intensity (Imax) was found to be proportional to berberine content at the femtomole level. With the proposed technique, the content in tablets and the average excretion rates of berberine through human urine after oral administration could be satisfactorily monitored.

Berberine↗

PubMed2002

The human homologue of unc-93 maps to chromosome 6q27 - characterisation and analysis in sporadic epithelial ovarian cancer.

BACKGROUND: In sporadic ovarian cancer, we have previously reported allele loss at D6S193 (62%) on chromosome 6q27, which suggested the presence of a putative tumour suppressor gene. Based on our data and that from another group, the minimal region of allele loss was between D6S264 and D6S149 (7.4 cM). To identify the putative tumour suppressor gene, we established a physical map initially with YACs and subsequently with PACs/BACs from D6S264 to D6S149. To accelerate the identification of genes, we sequenced the entire contig of approximately 1.1 Mb. Seven genes were identified within the region of allele loss between D6S264 and D6S149. RESULTS: The human homologue of unc-93 (UNC93A) in C. elegans was identified to be within the interval of allele loss centromeric to D6S149. This gene is 24.5 kb and comprises of 8 exons. There are two transcripts with the shorter one due to splicing out of exon 4. It is expressed in testis, small intestine, spleen, prostate, and ovary. In a panel of 8 ovarian cancer cell lines, UNC93A expression was detected by RT-PCR which identified the two transcripts in 2/8 cell lines. The entire coding sequence was examined for mutations in a panel of ovarian tumours and ovarian cancer cell lines. Mutations were identified in exons 1, 3, 4, 5, 6 and 8. Only 3 mutations were identified specifically in the tumour. These included a c.452G>A (W151X) mutation in exon 3, c.676C>T (R226X) in exon 5 and c.1225G>A(V409I) mutation in exon 8. However, the mutations in exon 3 and 5 were also present in 6% and 2% of the normal population respectively. The UNC93A cDNA was shown to express at the cell membrane and encodes for a protein of 60 kDa. CONCLUSIONS: These results suggest that no evidence for UNC93A as a tumour suppressor gene in sporadic ovarian cancer has been identified and further research is required to evaluate its normal function and role in the pathogenesis of ovarian cancer.

Amino Acid Sequence↗

PubMed2002

Immune surveillance and effector functions of CCR10(+) skin homing T cells.

Skin homing T cells carry memory for cutaneous Ags and play an important sentinel and effector role in host defense against pathogens that enter via the skin. CCR10 is a chemokine receptor that is preferentially expressed among blood leukocytes by a subset of memory CD4 and CD8 T cells that coexpress the skin-homing receptor cutaneous lymphocyte Ag (CLA), but not the gut-homing receptor alpha(4)beta(7). Homing and chemokine receptor coexpression studies detailed in this study suggest that the CLA(+)/CCR10(+) memory CD4 T cell population contains members that have access to both secondary lymphoid organ and skin compartments; and therefore, can act as both "central" and "effector" memory T cells. Consistent with this effector phenotype, CLA(+)/CCR10(+) memory CD4 T cells from normal donors secrete TNF and IFN-gamma but minimal IL-4 and IL-10 following in vitro stimulation. Interactions of CCR10 and its skin-associated ligand CC ligand 27 may play an important role in facilitating memory T cell entry into cutaneous sites during times of inflammation.

Animals↗

PubMed2002

Yeast cells lacking the ARV1 gene harbor defects in sphingolipid metabolism. Complementation by human ARV1.

arv1Delta mutant cells have an altered sterol distribution within cell membranes (Tinkelenberg, A.H., Liu, Y., Alcantara, F., Khan, S., Guo, Z., Bard, M., and Sturley, S. L. (2000) J. Biol. Chem. 275, 40667-40670), and thus it has been suggested that Arv1p may be involved in the trafficking of sterol in the yeast Saccharomyces cerevisiae and also in humans. Here we present data showing that arv1Delta mutants also harbor defects in sphingolipid metabolism. [(3)H]inositol and [(3)H]dihydrosphingosine radiolabeling studies demonstrated that mutant cells had reduced rates of biosynthesis and lower steady-state levels of complex sphingolipids while accumulating certain hydroxylated ceramide species. Phospholipid radiolabeling studies showed that arv1Delta cells harbored defects in the rates of biosynthesis and steady-state levels of phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, and phosphatidylglycerol. Neutral lipid radiolabeling studies indicated that the rate of biosynthesis and steady-state levels of sterol ester were increased in arv1Delta cells. Moreover, these same studies demonstrated that arv1Delta cells had decreased rates of biosynthesis and steady-state levels of total fatty acid and fatty acid alcohols. Gas chromatography/mass spectrometry analyses examining different fatty acid species showed that arv1Delta cells had decreased levels of C18:1 fatty acid. Additional gas chromatography/mass spectrometry analyses determining the levels of various molecular sterol species in arv1Delta cells showed that mutant cells accumulated early sterol intermediates. Using fluorescence microscopy we found that GFP-Arv1p localizes to the endoplasmic reticulum and Golgi. Interestingly, the heterologous expression of the human ARV1 cDNA suppressed the sphingolipid metabolic defects of arv1Delta cells. We hypothesize that in eukaryotic cells, Arv1p functions in the sphingolipid metabolic pathway perhaps as a transporter of ceramides between the endoplasmic reticulum and Golgi.

Ceramides↗

PubMed2002

Estradiol enhances Akt activation in cortical explant cultures following neuronal injury.

We have previously demonstrated that estradiol reduces cell death in cortical explant cultures following injury induced by metabolic inhibition in a receptor-dependent fashion. In this study, we examined whether cell death involves apoptosis and assessed the potential mediators of estradiol's actions. Cortical explant cultures were generated from postnatal day 3 rat pups. On day 7 in vitro, explants were injured by exposure to 1 mM 2-DG/2 mM KCN for 2 h to model the metabolic inhibition observed during ischemia. Explants were fixed in 4% paraformaldehyde at 2, 6, 10 and 24 h following the injury period and 18-microm thick sections were cut on a cryostat and stained with cresyl violet to assess cell death. The same sections were also labeled by TUNEL to determine whether cell death occurred by apoptosis. Other sections were used for immunohistochemistry to determine whether cells that stained positive for activated caspase 3 were also immunopositive for NeuN, a neuronal marker, or GFAP, an astrocyte marker. Protein was extracted for Western blot analysis from a separate set of explants collected at 0, 0.5, 1, 2 and 4 h following the conclusion of the injury. Estradiol treatment significantly reduced the number of cells undergoing apoptotic cell death as indicated by nuclear condensation visualized by cresyl violet staining (P<0.05). TUNEL staining revealed that the majority of pyknotic and fragmented nuclei were also TUNEL positive. Furthermore, caspase 3 activation appeared to be restricted to neurons. To examine a possible mechanism by which estradiol prevents apoptosis, we examined the level of activation of Akt kinase, which mediates antiapoptotic signals. Potential activation was measured by phosphorylation of Akt at Ser473 by Western blot analysis. In the absence of estradiol, pAkt levels were significantly increased at 2 h following the termination of injury. Explants that were pretreated with estradiol exhibited elevated levels of pAkt at 1 h following injury. Treatment with ICI 182,780 prevented the effect of estradiol. These studies suggest that estradiol prevents injury-induced apoptosis and that Akt activation may mediate these protective effects.

Alzheimer Disease↗

PubMed2002

Synthesis and cytotoxicity of 2alpha-amido docetaxel analogues.

Various 2-amido docetaxel analogues were prepared and evaluated for their cytotoxicities. Among them, m-methoxy and m-chlorobenzoylamido analogues were most active but not superior to docetaxel and paclitaxel, and D-seco analogues inactive. Change of 2-benzoate to 2-benzamide may not improve their activities to drug-resistant cell lines.

Antineoplastic Agents, Phytogenic↗

PubMed2002

Separation of chiral sulfoxides by liquid chromatography using macrocyclic glycopeptide chiral stationary phases.

A set of 42 chiral compounds containing stereogenic sulfur was prepared. There were 31 chiral sulfoxide compounds, three tosylated sulfilimines and eight sulfinate esters. The separations were done using five different macrocyclic glycopeptide chiral stationary phases (CSPs), namely ristocetin A, teicoplanin, teicoplanin aglycone (TAG), vancomycin and vancomycin aglycone (VAG) and seven eluents, three normal-phase mobile phases, two reversed phases and two polar organic mobile phases. Altogether the macrocyclic glycopeptide CSPs were able to separate the whole set of the 34 sulfoxide enantiomers and tosylated derivatives. Five of the eight sulfinate esters were also separated. The teicoplanin and TAG CSPs were the most effective CSPs able to resolve 35 and 33 of the 42 compounds. The three other CSPs each were able to resolve more than 27 compounds. The normal-phase mode was the most effective followed by the reversed-phase mode with methanol-water mobile phases. Few of these compounds could be separated in the polar organic mode with 100% methanol mobile phases. Acetonitrile was also not a good solvent for the resolution of enantiomers of sulfur-containing compounds, neither in the reversed-phase nor in the polar organic mode. The structure of the chiral molecules was compared to the enantioselectivity factors obtained with the teicoplanin and TAG CSP. It is shown that the polarity, volume and shape of the sulfoxide substituents influence the solute enantioselectivity factor. Changing the oxidation state of the sulfur atom from sulfoxides to sulfinate esters is detrimental to the compound's enantioselectivity. The enantiomeric retention order on the teicoplanin and TAG CSPs was very consistent: the (S)-(+)-sulfoxide enantiomer was always the less retained enantiomer. In contrast, the (R)-(-)-enantiomer was less retained by the ristocetin A, vancomycin and vancomycin aglycone columns, showing the complementarity of these CSPs. The macrocyclic glycopeptide CSPs provided broad selectivity and effective separations of chiral sulfoxides.

Chromatography, Liquid↗

PubMed2002

HIV-1 Tat protein-mediated transactivation of the HIV-1 long terminal repeat promoter is potentiated by a novel nuclear Tat-interacting protein of 110 kDa, Tip110.

Human immunodeficiency virus type 1 (HIV-1) gene expression and replication is highly dependent on and modulated by interactions between viral and host cellular factors. Tat protein, encoded by one of the HIV-1 regulatory genes, tat, is essential for HIV-1 gene expression. A number of host cellular factors have been shown to interact with Tat in this process. During our attempts to determine the molecular mechanisms of Tat interaction with brain cells, we isolated a cDNA clone that encodes a novel Tat-interacting protein of 110 kDa or Tip110 from a human fetal brain cDNA library. GenBank BLAST search revealed that Tip110 was almost identical to a previously cloned KIAA0156 gene with unknown functions. In vivo binding of Tip110 with Tat was confirmed by immunoprecipitation and Western blotting, in combination with mutagenesis. The yeast three-hybrid RNA-protein interaction assay indicated no direct interaction of Tip110 with Tat transactivating response element RNA. Nevertheless, Tip110 strongly synergized with Tat on Tat-mediated chloramphenicol acetyltransferase reporter gene expression and HIV-1 virus production, whereas down-modulation of constitutive Tip110 expression inhibited HIV-1 virus production. Northern blot analysis showed that Tip110 mRNA was expressed in a variety of human tissues and cells. Moreover, digital fluorescence microscopic imaging revealed that Tip110 was expressed exclusively in the nucleus, and within a nuclear speckle structure that has recently been described for human cyclin T and CDK9, two critical components for Tat transactivation function on HIV-1 long terminal repeat promoter. Taken together, these data demonstrate that Tip110 regulates Tat transactivation activity through direct interaction, and suggest that Tip110 is an important cellular factor for HIV-1 gene expression and viral replication.

Amino Acid Sequence↗

PubMed2002

[Transesophageal intraluminal ultrasonography in diagnosis and differential diagnosis of esophageal leiomyoma].

OBJECTIVE: To evaluate the diagnostic and differential diagnostic values of transesophageal echo probe (TEEP) or endoscopic ultrasonography (EUS) in the diagnosis and differential diagnosis of esophageal leiomyoma. METHODS: Between September 1996 and August 2000, TEEP or EUS was used among 23 patients with esophageal submucosal tumor and 11 patients with esophagus constricted from outside, among which 32 cases underwent CT too. All the patients except and 3 with constriction by aorta underwent surgical treatment. RESULTS: (1) The accuracy rate of diagnosis of esophageal leiomyoma by TEEP or EUS was 95.7% (22/23) in comparison with that by CT of only 42.9% (9/21, chi(2) = 14.69, P = 0.0196). (2) In the 11 patients with esophagi constricted by masses beyond or around esophagus, TEEP or EUS definitely differentiated the damage beyond or around esophagus from esophageal leiomyoma. CONCLUSION: Transesophageal intraluminal ultrasonography (TEEP and EUS) is a reliable method for the preoperative diagnosis and differential diagnosis of esophageal leiomyoma and is more accurate than CT.

Adult↗

PubMed2002

[Relationship between HLA-DQA1, -DQB1 genes polymorphism and susceptilibity to bronchial asthma among Northern Hans].

OBJECTIVE: To investigate the relationship between human leukocyte antigen (HLA)- DQA1, -DQB1 genes polymorphism and susceptibility to bronchial asthma among the Hans in the northern China. METHOD: Sequence-specific primer polymerase chain reaction was used to gene frequencies of HLA-DQA1 and HLA-DQB1 genes among 125 unrelated asthmatics, 12 of which being probands of asthmatic pedigrees, and 96 healthy controls, all of Han nationality and living in Beijing or nearby areas for a long time. Radioimmunosorbent test was used to examine the serum IgE and TigE. The ventilatory function was test among the asthmatics. RESULTS: The frequencies of HLA-DQA1 0104 and HLA-DQB1 0201 were 0.204 and 0.284, significantly higher than those in the healthy controls (0.089 and 0.096 respectively, both P < 0.01). Conversely, the frequencies of HLA-DQA10301 and HLA DQB101301 in the asthmatics were 0.148 and 0.20, significantly lower than those in the controls (0.25 and 0.282 respectively, P < 0.01 and < 0.05). The correlation coefficients between HLA-DQA1 * 0104 and atopy, HLA-DQB1 * 0201 and atopy, and HLA-DQA1 * 0301 and atopy were 0.813 (P < 0.01), 0.289 (P < 0.01), and -0.168 (P < 0.05) respectively. Multi-variate logistic regression asthma. CONCLUSIONS: The alleles HLA-DQA1 * 0104 and HLA-DQB1 * 0201 are correlated with the susceptibility to asthma among Northern of Han nationality. HLA-DQA1 * 0104 is an independent risk factor of onset of asthma. The alleles HLA-DQA1 * 0301 and HLA-DQB10301 are correlated with resistance against asthma. HLA-DQ genes are involved in the regulation of human specific immune responses.

Adult↗

PubMed2002

Lipid rafts orchestrate signaling by the platelet receptor glycoprotein VI.

The platelet collagen receptor glycoprotein VI (GPVI) couples to the immune receptor adaptor Fc receptor gamma-chain (FcRgamma) and signals using many of the same intracellular signaling molecules as immune receptors. Studies of immune receptor signaling have revealed a critical role for specialized areas of the cell membrane known as lipid rafts, which are enriched in essential signaling molecules. However, the role of lipid rafts in signaling in nonimmune cells such as platelets remains poorly defined. This study shows that GPVI-FcRgamma does not constitutively associate with rafts, but is recruited to lipid rafts following receptor stimulation in both GPVI-expressing RBL-2H3 cells and human platelets. FcRgamma is required for GPVI association with lipid rafts, as mutant GPVI receptors that do not couple to FcRgamma were unable to associate with lipid rafts after receptor clustering. Following GPVI stimulation in platelets, virtually all phosphorylated FcRgamma was found in lipid rafts, but inhibition of FcRgamma phosphorylation did not block receptor association with lipid rafts. This work demonstrates that lipid rafts orchestrate GPVI receptor signaling in platelets in a manner analogous to immune cell receptors and supports a model of GPVI signaling in which FcRgamma phosphorylation is controlled by ligand-dependent association with lipid rafts.

3T3 Cells↗

PubMed2002

Draining lymph nodes of corneal transplant hosts exhibit evidence for donor major histocompatibility complex (MHC) class II-positive dendritic cells derived from MHC class II-negative grafts.

To examine the widely accepted dogmas that corneal grafts lack passenger leukocytes or cells capable of migrating directly to lymph nodes (LNs), we tracked the migration of corneal graft-derived transgenic green fluorescent protein (GFP; Ia(b)) cells into the draining LNs of allogeneic (Ia(d)) recipients. GFP(+) cells were identified in cervical LNs several hours after transplantation, and this traffic was significantly enhanced when grafts were placed in inflamed recipient beds. Draining cells were Ia(b+), CD45(+), and CD11c(+), and examination of ungrafted corneas revealed numerous similarly CD45(+)CD11c(+)CD3(-)CD8alpha(-) cells that uniformly lacked major histocompatibility complex (MHC) class II expression; transmission electron microscopy confirmed the presence of morphologically similar cells. After transplantation, or placement in culture, these CD11c(+) cells became class II(+) in a time-dependent manner and were capable of allostimulatory function. However, the stimulatory capacity of these cornea-derived dendritic cells (DCs) was suppressed compared with splenic controls. These results demonstrate for the first time that the cornea is endowed with resident DCs that are universally MHC class II(-) but that are capable of expressing class II antigen after surgery and migrating to draining LNs of allografted hosts. These data refute the tenet that the cornea is immune privileged due to lack of resident lymphoreticular cells or due to antigenic sequestration from systemic immunity.

Animals↗