Biomedical subjects

J Qian

Publications and source records attributed to J Qian.

At least 73 records · Page 4Linked to original sources

PubMed2000

[Immunological study on the antitumor effects of fungus polysaccharides compounds].

Fungus polysaccharides compounds (FPC) are the mixture of procyanidins oligomers, glycyrrhetinicacid and polysaccharides of hericium erinaceus, lentinus edodes and poria cocos. The antitumor effects of FPC and its immunity regulating effects as an immunostimulant on the mice burdened with sarcoma 180 (S-180) were studied. FPC (100, 200 and 400 mg/kg BW) was gavaged to mice for 31 days. S-180 was transplanted to these mice on the 21th day. Lentinus edodes group was gavaged 200 mg/kg BW saccharine of lentinus edodes. The results showed that FPC could inhibit the growth of S-180 effectively. The inhibitory rates were 37.74%, 44.73% and 48.32% respectively. The antineoplastic activity of FPC (200 mg/kg. BW) was more effective than polysaccharide of lentinus edodes at the same dose. In S-180 burdened mice, the percentage of L3T4 and the ratio of L3T4/Lyt-2, NK activity and the induced IL-2, IFN-gamma levels were decreased significantly compared with the normal control group. As an immunostimulant, FPC could increase the percentage of L3T4 and the ratio of L3T4/Lyt-2 in S-180 burdened mice, but had no significant effects on the percentage of Lyt-2. Polysaccharide of lentinus edodes alone could also increase the immunity competence of mice burdened with S-180, but was not better than that of FPC at the same dose. It could be concluded that the compound of antineoplastic component could be synergetic.

Adjuvants, Immunologic↗

PubMed2000

Where is 'outside' in cytochrome c oxidase and how and when do protons get there?

Cytochrome c oxidase moves both electrons and protons in its dual role as a terminal electron acceptor and a contributor to the proton motive force which drives the formation of ATP. Although the sequence of electron transfer events is well-defined, the correlated mechanism and routes by which protons are translocated across the membrane are not. A recent model [Michel, Proc. Natl. Acad. Sci. USA 95 (1998) 12819] offers a detailed molecular description of when and how protons are translocated through the protein to the outside, which contrasts with previous models in several respects. This article reviews the behavior of site-directed mutants of Rhodobacter sphaeroides cytochrome c oxidase in the context of these different models. Studies of the internally located lysine 362 on the K channel and aspartate 132 on the D channel, indicate that D132, but not K362, is connected to the exterior region. Analysis of the externally located arginine pair, 481 and 482, and the Mg/Mn ligands, histidine 411 and aspartate 412, which are part of the hydrogen-bonded network that includes the heme propionates, indicates that alterations in this region do not strongly compromise proton pumping, but do influence the pH dependence of overall activity and the control of activity by the pH gradient. The results are suggestive of a region of 'sequestered' protons: beyond a major energetic gate, but selectively responsive to the external environment.

Aspartic Acid↗

PubMed2000

Prevention and treatment of factor VIII inhibitors in murine hemophilia A.

Inhibitory antibody formation is a major complication of factor VIII replacement therapy in patients with hemophilia A. To better understand the pathogenesis of this immunologic reaction, we evaluated the role of T-cell costimulatory signals for antifactor VIII antibody formation in a murine model of hemophilia A. Repeated intravenous injections of factor VIII in these factor VIII-deficient mice induced an antifactor VIII inhibitor antibody response. This response was shown to be T-cell dependent by its absence in hemophilic mice also deficient for the T-cell costimulatory ligand B7-2. In separate experiments, injection of murine CTLA4-Ig completely blocked the primary response to factor VIII in hemophilic mice with intact B7 function. This reagent also prevented or diminished further increases in antifactor VIII when given to hemophilic mice with low antifactor VIII antibody titers. These studies suggest that strategies targeting the B7-CD28 pathway are potential therapies to prevent and treat inhibitory antifactor VIII antibodies. Moreover, because the development of antibodies to replaced proteins may limit the success of many human gene therapy approaches, our results may be broadly applicable. (Blood. 2000;95:1324-1329)

Abatacept↗

PubMed2000

Closure approach to high-order structure functions of turbulence

Let T(p) be the structure function of order p of turbulence. First T2 is determined, then T3 is derived from T2, and finally T(p) (p>3) are derived from T2 and T3. This closure scheme is realized by a non-Gaussian statistical model. We use it to study the scaling law of T(p), and we find that the available data on scaling exponents favor Kolmogorov's 1941 theory rather than his 1962 theory. We also predict the high-order universal constants of inertial-range scaling.

Journal Article↗

PubMed2000

Increased expression of preprotachykinin-I and neurokinin receptors in human breast cancer cells: implications for bone marrow metastasis.

Neuropeptides are implicated in many tumors, breast cancer (BC) included. Preprotachykinin-I (PPT-I) encodes multiple neuropeptides with pleiotropic functions such as neurotransmission, immune/hematopoietic modulation, angiogenesis, and mitogenesis. PPT-I is constitutively expressed in some tumors. In this study, we investigated a role for PPT-I and its receptors, neurokinin-1 (NK-1) and NK-2, in BC by using quantitative reverse transcription-PCR, ELISA, and in situ hybridization. Compared with normal mammary epithelial cells (n = 2) and benign breast biopsies (n = 21), BC cell lines (n = 7) and malignant breast biopsies (n = 25) showed increased expression of PPT-I and NK-1. NK-2 levels were high in normal and malignant cells. Specific NK-1 and NK-2 antagonists inhibited BC cell proliferation, suggesting autocrine and/or intercrine stimulation of BC cells by PPT-I peptides. NK-2 showed no effect on the proliferation of normal cells but mediated the proliferation of BC cells. Cytosolic extracts from malignant BC cells enhanced PPT-I translation whereas extracts from normal mammary epithelial cells caused no change. These enhancing effects may be protein-specific because a similar increase was observed for IL-6 translation and no effect was observed for IL-1alpha and stem cell factor. The data suggest that PPT-I peptides and their receptors may be important in BC development. Considering that PPT-I peptides are hematopoietic modulators, these results could be extended to understand early integration of BC cells in the bone marrow, a preferred site of metastasis. Molecular signaling transduced by PPT-I peptides and the mechanism that enhances translation of PPT-I mRNA could lead to innovative strategies for BC treatments and metastasis.

Benzamides↗

PubMed2000

Presynaptic Ca(2+) influx at a mouse central synapse with Ca(2+) channel subunit mutations.

Genetic alterations in Ca(2+) channel subunits can be used to study the interaction among channel subunits and their roles in channel function. P/Q- and N-type Ca(2+) channels reside at the presynaptic terminal and control the release of neurotransmitter at mammalian central synapses. We used fluorescence imaging techniques to investigate presynaptic Ca(2+) currents and neurotransmitter release at hippocampal Schaffer collateral synapses in both tottering (tg, alpha(1A) subunit) and lethargic (lh, beta(4) subunit) mutant mice. Application of selective toxins revealed a large reduction in presynaptic P/Q-type Ca(2+) transients, from 39% of total in +/+ mice to 6% in tg/tg mice, whereas the proportion of N-type increased from 35 to 68%, respectively. Neurotransmitter release in the tg/tg mutant relied almost exclusively on N-type channels, as shown by the complete blockade of synaptic transmission with omega-conotoxin GVIA. Remarkably, loss of beta4, a subunit predicted to regulate the subcellular targeting and modulation of both P/Q- and N-type channels, resulted in no significant difference in the ratio of Ca(2+) channel subtypes or Ca(2+) dependence of neurotransmitter release in lethargic mice. G-protein-mediated inhibition of Ca(2+) channels was also unaltered. These results indicate that a profound decrease in presynaptic P/Q-type currents leads to dependence of neurotransmitter release on N-type channels. In contrast, absence of beta(4) appears not to compromise either P/Q- or N-type channel function at this hippocampal synapse, implicating rescue of presynaptic Ca(2+) currents by other available beta subunits. The present study reveals compensatory molecular mechanisms in the regulation of presynaptic Ca(2+) entry and neurotransmitter release.

2-Amino-5-phosphonovalerate↗

PubMed2000

Loss of expression of the DRR 1 gene at chromosomal segment 3p21.1 in renal cell carcinoma.

Consistent deletion of DNA sequences in chromosomal band 3p21 observed in a variety of human tumors suggests the presence of one or more tumor suppressor genes within this region. Previously, we reported on the construction of two distinct cosmid contigs and our identification of several new genes within 3p21.1. In our search for tumor suppressor genes from this region, we have cloned a gene that we have called DRR 1 (downregulated in renal cell carcinoma). The gene was first mapped to 3p21.1 by fluorescence in situ hybridization analysis. Further analysis of yeast artificial chromosome clones in 3p14.2-p21.1 refined its localization. DRR 1 spans about 10 Kb of genomic DNA with a 3.5-Kb mature transcript. The putative protein encoded by this gene is 144 amino acids and includes a nuclear localization signal and a coiled domain. The gene showed loss of expression in eight of eight renal cell carcinoma cell lines, one of seven ovarian cancer cell lines, one of one cervical cancer cell line, one of one gastric cancer cell line, and one of one non-small-cell lung cancer cell line. Southern blot analysis did not show any altered bands, indicating that gross structural changes or deletions did not cause the loss of expression. This gene was also found to have reduced expression in 23 of 34 paired primary renal cell carcinomas. Mutational analysis detected three polymorphic sites within the gene, but no point mutations were identified in the 34 primary tumors. However, we did detect base substitutions in 4 of 12 cell lines that had undetectable expression of the gene. We also transfected the gene into DRR 1-negative cell lines and observed clear growth retardation. Our results suggest that loss of expression of the DRR 1 gene may play an important role in the development of renal cell carcinoma and possibly other tumors. Genes Chromosomes Cancer 27:1-10, 2000.

Amino Acid Sequence↗

PubMed2000

Coamplification of prostate stem cell antigen (PSCA) and MYC in locally advanced prostate cancer.

Gain of sequences on chromosome arm 8q is a common feature of prostate cancer that may correlate with metastatic and androgen-independent progression. The target gene(s) for this gain is not known, although MYC is amplified in a subset of advanced tumors and is one potential candidate. Prostate stem cell antigen (PSCA) is a prostate-specific cell surface protein that maps to chromosome region 8q24.2 and is overexpressed in prostate cancer. Our aim in this study was to test the hypothesis that PSCA overexpression may result from overrepresentation of chromosome arm 8q. Twenty locally advanced prostate cancers were analyzed by dual-probe fluorescence in situ hybridization (FISH) for alterations of MYC and PSCA. Extra copies of MYC were found in 12/20 (60%) tumors, including 5 (25%) with simple gain (no increase in MYC copy number relative to the chromosome 8 centromere) and 7 (35%) with an additional increase (AI or overrepresentation) in MYC copy number relative to the centromere. In the five cases with simple gain of MYC, there was a concomitant gain of PSCA. PSCA was overrepresented in 5/7 (71%) cases with AI of MYC. Immunohistochemical staining of the 20 tumors with monoclonal antibodies specific for PSCA showed a high degree of correlation between PSCA gene overrepresentation and protein overexpression. Four of 5 tumors with AI of PSCA overexpressed PSCA protein, compared with only 2/15 tumors with a normal PSCA copy number or simple gain of PSCA (P = 0.014). These results demonstrate that PSCA is co-overrepresented with MYC in a majority of cases, but may not be a necessary part of the 8q amplicon. PSCA protein overexpression can result from AI of PSCA and might be useful as a cell surface marker on prostate cancer cells with 8q overrepresentation. Genes Chromosomes Cancer 27:95-103, 2000.

Antigens, Neoplasm↗

PubMed2000

Mapping of the chromosome 19 q-arm glioma tumor suppressor gene using fluorescence in situ hybridization and novel microsatellite markers.

Allelic loss of chromosome arm 19q is a frequent event in human diffuse glioma, suggesting the presence of a tumor suppressor gene. Previous loss of heterozygosity (LOH) analyses have mapped this gene to a 1.4-megabase interval, between the genetic markers D19S412 and STD. Further narrowing of this interval has been limited by the resolution of mapped polymorphic markers. In the present study, we have used genomic clones mapped to 19q as fluorescence in situ hybridization (FISH) probes to map the breakpoints of 13 gliomas with 19q13.3 deletion boundaries. In addition, we have developed three new polymorphic microsatellite markers (D19S1180, D19S1181, and D19S1182) that map between D19S412 and STD and have used these new markers to identify two gliomas with small deletions between the D19S412 and STD markers. Collectively, these data suggest that the region of common deletion may be as narrow as 150 kb and should facilitate future efforts to identify the glioma 19q tumor suppressor gene.

Chromosome Deletion↗

PubMed2000

Role of CD154 in the secondary immune response: the reduction of pre-existing splenic germinal centers and anti-factor VIII inhibitor titer.

Using the murine model of hemophilia A, we have examined the role of CD154 in the secondary immune response to factor VIII (FVIII). We previously reported that repeated i.v. injection of FVIII in hemophilia A mice induces a T cell-dependent anti-FVIII antibody formation. Herein, blocking of CD154 by a monoclonal antibody in FVIII-primed hemophilia A mice resulted in the disappearance of pre-existing spleen germinal centers (GC) in the white pulp within 24 h of treatment. Moreover, further expansion of GC in response to FVIII challenge was completely inhibited. In parallel, anti-FVIII antibody titers were markedly reduced and T cell responses to FVIII were abolished. The rapid disappearance of the GC after anti-CD154 treatment was not accompanied by increased B cell apoptosis; instead B cells accumulated in the peripheral zone of the splenic white pulp. Interestingly, repeated exposure to FVIII with anti-CD154 antibody administration blocked anti-FVIII antibody formation but failed to induce long-lasting unresponsiveness. Our data demonstrate that the CD40-CD154 interaction is critical for B cell homeostasis and the secondary immune response to FVIII. For potential clinical application, the data also suggest that therapies targeting the CD154 molecule may be useful for the treatment of high titer FVIII inhibitors in hemophilia A.

Animals↗

PubMed2000

Efficiency of solvent extraction methods for the determination of methyl mercury in forest soils.

Methyl mercury was determined by gas chromatography, microwave induced plasma, atomic emission spectrometry (GC-MIP-AES) using two different methods. One was based on extraction of mercury species into toluene, pre-concentration by evaporation and butylation of methyl mercury with a Grignard reagent followed by determination. With the other, methyl mercury was extracted into dichloromethane and back extracted into water followed by in situ ethylation, collection of ethylated mercury species on Tenax and determination. The accuracy of the entire procedure based on butylation was validated for the individual steps involved in the method. Methyl mercury added to various types of soil samples showed an overall average recovery of 87.5%. Reduced recovery was only caused by losses of methyl mercury during extraction into toluene and during pre-concentration by evaporation. The extraction of methyl mercury added to the soil was therefore quantitative. Since it is not possible to directly determine the extraction efficiency of incipient methyl mercury, the extraction efficiency of total mercury with an acidified solution containing CuSO4 and KBr was compared with high-pressure microwave acid digestion. The solvent extraction efficiency was 93%. For the IAEA 356 sediment certified reference material, mercury was less efficiently extracted and determined methyl mercury concentrations were below the certified value. Incomplete extraction could be explained by the presence of a large part of inorganic sulfides, as determined by x-ray absorption near-edge structure spectroscopy (XANES). Analyses of sediment reference material CRM 580 gave results in agreement with the certified value. The butylation method gave a detection limit for methyl mercury of 0.1 ng g(-1), calculated as three times the standard deviation for repeated analysis of soil samples. Lower values were obtained with the ethylation method. The precision, expressed as RSD for concentrations 20 times above the detection limit, was typically 5%.

Bromides↗

PubMed2000

Molecular dynamics and (2)H-NMR study of the influence of an amphiphilic peptide on membrane order and dynamics.

A molecular dynamics simulation of a fully hydrated model membrane consisting of 12 molecules of 1, 2-dimyristoyl-sn-glycero-3-phosphocholine, one amphiphilic peptide with the sequence acetyl-Lys-Lys-Gly-Leu(16)-Lys-Lys-Ala-amide, and 593 water molecules was performed for 1.06 ns (Belohorcova, K., J. H. Davis, T. B. Woolf, and B. Roux. 1997. Biophys. J. 73:3039-3055). The analysis presented here is primarily focused on the phospholipid component and the results are compared with experimental (2)H-NMR studies of the lipid component of mixtures of the same peptide and lipid at a molar ratio of 1:32, and with earlier studies of closely related peptide/lipid mixtures. The phospholipid chain and headgroup isomer populations and isomerization rates compare favorably with previous simulations and experimental measurements. Of particular interest is the effect of the peptide on the phospholipid headgroup and hydrocarbon chain orientational order calculated from the simulation, which also agree well with experimental measurements performed on this and closely related systems. Comparison of the experimental results with the simulations not only shows that there is significant agreement between the two methods, but also provides new insight into the effect of the peptide on the lipid dynamics. In particular, these results confirm that a membrane spanning peptide has little effect on lipid chain order, and bilayer thickness if its hydrophobic length closely matches the lipid hydrocarbon thickness. In addition, we find that the peptide can have a strong ordering effect if it is longer than the lipid hydrophobic thickness.

Amino Acid Sequence↗

PubMed2000

An indirect role for upstream stimulatory factor in glucose-mediated induction of pyruvate kinase and S14 gene expression.

Transcription of the L-type pyruvate kinase (L-PK) and S14 genes is induced in hepatocytes in response to increased glucose metabolism. The regulatory sequences of these genes responsible for induction by glucose have been mapped to related E-box containing motifs in the promoters. Similarly, L-PK promoter activity is stimulated in a differentiated pancreatic beta-cell line, INS-1, in response to elevated glucose. By mutational analysis, we demonstrate that the sequence requirements for glucose induction in the INS-1 cell are identical to those observed in the hepatocyte, suggesting that the same transcriptional factor(s) is responsible for regulation of L-PK expression in the two cell types. One nuclear factor that binds to the glucose regulatory sequences of both of these genes is the Upstream Stimulatory Factor (USF), a ubiquitous E-box binding protein. Mice deleted for the USF2 gene display a severely delayed response to carbohydrate feeding (Vallet et al. [26]). This observation, however, does not differentiate between a direct and an indirect role for USF in the process. To gain further insight into the possible involvement of USF in glucose signaling, we have used a recombinant adenoviral construct that expresses a dominant negative form of USF. This dominant negative can dimerize with endogenous USF and is shown to inhibit DNA binding of USF in hepatocytes and INS-1 cells. However, expression of the dominant negative USF did not block the ability of glucose to stimulate L-PK or S14 gene expression in hepatocytes or L-PK promoter activity in INS-1 cells. We conclude that USF does not act by binding to the glucose regulatory sequences of the S14 or L-PK genes and the role of USF in the process of glucose induction is indirect.

Adenoviridae↗

PubMed2000

Crystal structures of the photosystem II D1 C-terminal processing protease.

We report here the first three-dimensional structure of the D1 C-terminal processing protease (D1P), which is encoded by the ctpA gene. This enzyme removes the C-terminal extension of the D1 polypeptide of photosystem II of oxygenic photosynthesis. Proteolytic processing is necessary to allow the light driven assembly of the tetranuclear manganese cluster, which is responsible for photosynthetic water oxidation. The X-ray structure of the Scenedesmus obliquus enzyme has been determined at 1.8 A resolution using the multiwavelength anomalous dispersion method. The enzyme is monomeric and is composed of three folding domains. The middle domain is topologically homologous to known PDZ motifs and is proposed to be the site at which the substrate C-terminus binds. The remainder of the substrate likely extends across the face of the enzyme, interacting at its scissile bond with the enzyme active site Ser 372 / Lys 397 catalytic dyad, which lies at the center of the protein at the interface of the three domains.

Algal Proteins↗

PubMed2000

Safety of intracoronary Doppler flow measurement.

BACKGROUND: With the introduction of Doppler-tipped guide wires, intracoronary Doppler flow measurement has been increasingly accepted as an additional diagnostic approach in the catheterization laboratory. However, the safety of intracoronary Doppler flow measurement has not been well-investigated. The purpose of our study was to evaluate the safety of intracoronary Doppler flow measurement using the Doppler FloWire (Cardiometrics, Mountain View, Calif). METHODS AND RESULTS: A total of 906 patients were examined by intracoronary Doppler with a 0.014-inch or an 0.018-inch Doppler FloWire. For coronary flow reserve measurement, intracoronary injection of adenosine or papaverine was used. Of the patients studied, 77 were cardiac transplant recipients and 829 were patients who had not received a transplant, of whom 617 had undergone diagnostic coronary procedures and 212 had coronary interventions. In 27 (2.98%) of 906 patients adverse cardiac events were observed. Fifteen (1.66%) of 906 patients had severe transient bradycardia develop (asystole or second- to third-degree atrioventricular block) after intracoronary administration of adenosine, 14 of which occurred in the right coronary artery and 1 in the left anterior descending artery. Nine (0.99%) of 906 patients had coronary spasm during the passage of the Doppler wire (5 in the right coronary artery, 4 in the left anterior descending artery). Two (0.22%) of 906 patients had ventricular fibrillation during the procedure. Hypotension with bradycardia and ventricular extrasystole each occurred in 1 (0.11%) of 906 patients. The incidence of complication was significantly higher in transplant recipients than in patients who underwent either diagnostic or interventional procedures (12.99% vs 2.43% vs 0.94%, P <.001). The Doppler measurements in the right coronary artery were associated with a higher incidence of complications, especially bradycardia, compared with the left anterior descending and the left circumflex arteries (right coronary, 5.87% vs left anterior descending, 1.05% vs left circumflex, 0.17%; P <.001). All complications were cured medically. CONCLUSION: Intracoronary Doppler flow measurement with Doppler wires and intracoronary administration of adenosine is a safe method. However, severe complications such as bradycardia and coronary spasm can occur. Attention should be paid to the examination of the right coronary artery, especially in heart transplant recipients.

Adenosine↗

PubMed2000

Amplification of the platelet-derived growth factor receptor-A (PDGFRA) gene occurs in oligodendrogliomas with grade IV anaplastic features.

Activation of the platelet-derived growth factor (PDGF) signaling system has been implicated in the development and malignant progression of diffuse gliomas. Overexpression of PDGF system components, particularly the alpha subtype receptor (PDGFRA), is common in glial tumors, and PDGFRA gene amplification has been reported in glioblastomas. In order to address the incidence of PDGFRA gene amplification in a broad set of diffuse gliomas, we used Southern and fluorescence in situ hybridization (FISH) analyses to examine 167 astrocytic gliomas (20 grade III and 147 grade IV), 41 anaplastic oligodendrogliomas, and 29 anaplastic oligoastrocytomas. PDGFRA gene amplification was identified in 4 anaplastic oligodendrogliomas and in a single case of anaplastic oligoastrocytoma, but in none of the malignant astrocytomas. Each of the 5 tumors with PDGFRA amplification displayed features generally associated with grade IV malignancy in astrocytic tumors. Consequently, our data indicate that this gene alteration is restricted to tumors having oligodendroglial differentiation and highly anaplastic features.

Blotting, Southern↗

PubMed2000

Effects of preprotachykinin-I peptides on hematopoietic homeostasis. A role for bone marrow endopeptidases.

Hematopoiesis is maintained by "fine-tuned" regulation among cytokines, neuropeptides, neurotransmitters, and neurotrophic factors. Neurotransmitters, derived from PPT-I exert immune and hematopoietic regulation. PPT-I is also expressed locally in bone marrow (BM) stromal cells. PPT-I peptides induce the production of cytokines in BM cells, resulting in regulation of both committed progenitors (CFU-GM) and primitive hematopoietic progenitors (CAFC). Both types of progenitors are regulated differently by the two major PPT-I peptides, SP and NK-A. Endopeptidases, present in BM cells, can digest SP to produce SP(1-4) and SP(4-11). In this study, we investigated the hematopoietic effects of these fragments on CFU-GM and CAFC. Similar to the two major intact PPT-I peptides (SP and NK-A), we observed different hematopoietic effects by SP(1-4) and SP(4-11). Whereas SP(1-4) exerted inhibitory effects on CFU-GM and CAFC, SP(4-11) mediated stimulatory effects. Similar to NK-A, the inhibitory effects of SP(1-4) can be partly explained by the induction of suppressive cytokines (TGF-beta, TNF-alpha, and INF-gamma). Use of antagonists and screening of a dodecapeptide expression library determined that the effects of SP(1-4) were mediated by NK-1. These results show that PPT-I peptides and their endopeptidase-derived fragments may add to the fine-tuned regulation on hematopoiesis. Furthermore, PPT-I may be exerting autoregulation to protect hematopoietic stem cells. These studies have relevance to stem cell protection and BM transplant.

Adult↗

PubMed2000

Characterization of the immune response to factor VIII using hemophilia A* mice.

Inhibitor antibody formation is a major complication of factor VIII replacement therapy in patients with hemophilia A. In order to understand the pathogenesis of this immunologic reaction better, we have characterized the immune response to human factor VIII in a murine model of hemophilia A. Mice with severe factor VIII deficiency caused by targeted gene disruptions were injected intravenously with human factor VIII. A human factor VIII-specific T-cell proliferative response was detected with spleen cells obtained three days after a single injection with human factor VIII and anti-factor VIII antibodies were detected after two intravenous injections. Subsequent exposures led to high titer anti-factor VIII antibodies in both ELISA and inhibitor assays. The anti-factor VIII inhibitor antibody response was shown to be T-cell dependent by its absence in hemophilic mice also deficient for the T-cell co-stimulatory ligand B7-2. In separate experiments, injection of murine CTLA4-Ig completely blocked the primary response to factor VIII in hemophilic mice with intact B7 function. This reagent also prevented or diminished further increases in anti-factor VIII when given to hemophilic mice with low anti-factor VIII antibody titers.

Abatacept↗