Detection of precursor Th cells in mesenteric lymph nodes after oral immunization with protein antigen and cholera toxin

We have characterized the earliest antigen-specific Th cells in murine mesenteric lymph nodes (MLN), following oral immunization with the hen egg lysozyme (HEL) as antigen and cholera toxin (CT) as adjuvant. We did this by analyzing in vitro proliferation and cytokine production in response to HEL by the MLN T cells. MLN cells taken 5 days after a single oral immunization with HEL and CT provided the earliest source of proliferating HEL-specific T cells. This proliferation was completely inhibited by anti-IL-2, but not inhibited by anti-IL-4 antibody. IL-2 protein was detected in culture supernatants but not IL- 4 using ELISA or bioassays. IL-4 mRNA was not found in responding cells using RT-PCR. Some of the day 5 MLN cultures produced IFN-gamma in response to HEL, but isolated T cells from the same MLN did not. Exogenous IL-4 alone did not stimulate day 5 MLN T cells, but IL-4 did synergize with HEL to induce a large proliferative response. The data indicate that the HEL-specific CD4 T cell pool in MLN 5 days after oral immunization is composed of undifferentiated precursor Th cells. These cells have the potential for IL-2 production and IL-4R expression upon re-stimulation in vitro.      

Blood clotting in minimally altered whole blood

The sequences of events regulating thrombin generation during tissue factor-initiated clotting in whole blood at 37 degrees C in which the contact pathway was suppressed with corn trypsin inhibitor are studied using quantitative Western blotting of factor V, prothrombin, platelet factor 4, antithrombin III, and fibrinogen. In addition, fibrinopeptide A (FPA), thrombin-antithrombin III (TAT) complex formation, and prothrombin fragment 1.2 (F1.2) were measured via commercially available enzyme-linked immunosorbent assays (ELISAs). In a typical experiment initiated with 40 pmol/L recombinant tissue factor, visual clot time (4.5 minutes), was preceded by significant cleavage of factor V resulting in 65% factor Va heavy-chain generation but only 10% light- chain formation. At this point, 50% of the platelet factor 4 is released, suggesting that half (approximately 700 pmol/L) of the platelet prothrombinase sites available have been generated. At clot time, approximately 15 nmol/L thrombin B-chain is present; however, analyses of FPA release demonstrate that only 15% of the thrombin is acting on fibrinogen. This thrombin is produced by the action of 7 pmol/L prothrombinase. The maximum rate of thrombin production is reached well after clot time and is consistent with the presence of approximately 150 pmol/L prothrombinase (at about 7 minutes). These results suggest that factor Xa is the limiting factor for thrombin generation. After 60 minutes, 75% of the initial prothrombin (1.24 mumol/L) is consumed yielding 400 nmol/ L prethrombin 2 and 360 nmol/l thrombin (B-chain) products. The sum of these values (800 nmol/L) is similar to the (corrected) F1.2 concentration determined by ELISA. The incomplete cleavage of prothrombin indicates both the prothrombinase complex and the formation of prothrombinase are inhibited in the reaction. TAT complex measured by ELISA is almost equivalent to B-chain concentration, but sodium dodecyl sulfate stable thrombin-antithrombin III complexes are not observed until well after clot formation and are never equivalent to ELISA-TAT values. At the point of clot formation, 80% of the fibrinogen is depleted from the fluid phase, whereas only 35% to 45% of the FPA is released, suggesting a significant incorporation of uncleaved fibrinogen into the initial clot formed.     

Allogeneic blood transfusion-induced enhancement of tumor growth: two animal models showing amelioration by leukodepletion and passive transfer using spleen cells [see comments]

Allogeneic blood transfusions have been reported to induce immunomodulation in recipients of blood products. While the mechanism(s) of this immunomodulatory effect is unknown, it has been suggested that this effect of allogeneic blood transfusions could adversely affect patients with a malignant disorder. These concerns have been supported by a number of nonrandomized, mainly retrospective, clinical studies which indicate that allogeneic blood transfusions can adversely affect prognosis following the surgical treatment of oncology patients. Recently, we have shown that allogeneic blood transfusions enhance primary tumor growth and increase metastatic pulmonary nodule formation in inbred mice. The tumor growth-promoting activity of allogeneic blood transfusions was studied also using outbred rabbits. In this present study, we demonstrate that the tumor growth-promoting effect of allogeneic blood transfusions is mediated by donor leukocytes and that this effect can be abolished by their removal before transfusion. We show also that the allogeneic blood transfusion tumor growth-promoting effect can be passively transferred to naive animals (both mice and rabbits) using spleen cells from allogeneically transfused animals. In these experiments, numbers of metastatic pulmonary nodules were significantly increased in both mice and rabbits that had received spleen cells from allogeneically transfused animals compared with those that had received spleen cells from syngeneically transfused animals, or from animals that had been transfused with leukodepleted allogeneic blood.     

Purification and characterization of factor VIII 1,689-Cys: a nonfunctional cofactor occurring in a patient with severe hemophilia A

We have purified the factor VIII from a CRM+ Hemophilia A plasma (90 U/dL VIII:Ag but 0 U/dL VIII:C) and analyzed the protein before and after thrombin activation by Western blotting with monoclonal antibodies (MoAbs). Normal or patient citrated plasma was ultracentrifuged, cryo-ethanol-precipitated and chromatographed on Sepharose 6B. The void volume fractions were reduced and subjected to ion exchange chromatography yielding material of specific activity approximately 1,000 U/mg protein (VIII:C or VIII:Ag). Factor VIII purified in this way from normal plasma is fully activatable by thrombin with proteolytic fragmentation as previously described by F. Rotblat et al (Biochemistry 24: 4294, 1985). Factor VIII 1,689-Cys has the normal distribution of factor VIII light and heavy chains prior to thrombin activation. After exposure to thrombin the heavy chain polypeptides were fully proteolysed but the light chain was totally resistant to cleavage. This is consistent with the demonstration in the patient's leucocyte DNA of a C to T transition in codon 1,689 converting Arg to Cys at the light chain thrombin cleavage site as previously described by J. Gitschier et al (Blood 72:1022, 1988). Uncleaved light chain of Factor VIII 1,689-Cys is not released from von Willebrand factor (vWF) by thrombin, but this is not the sole cause of the functional defect since the protein purified free of vWF has no coagulant activity. We conclude that the functional defect in factor VIII 1,689-Cys is a consequence of failure to release the acidic peptide from the light chain upon thrombin activation.     

荷载角质细胞生长因子纳米微囊脱细胞真皮的制备、特性及其对表皮干细胞群生长的作用

目的:构建一种荷载有角质细胞生长因子且能控制释放的新型组织工程化皮肤。方法:实验于2006-03/12于中山大学附属第二医院干细胞研究中心及中山大学高分子研究所进行。①材料:角质细胞生长因子(CytolLAB公司),牛血清白蛋白(Amresco公司),聚乳酸-羟基乙酸共聚物(由中山大学高分子化学研究所合成,聚乳酸与聚羟基乙酸摩尔比为75∶25,相对分子质量为50000),脱细胞真皮(北京桀亚莱福生物技术有限公司)。②方法:采用超声乳化-溶剂挥发及低温干燥方法,将角质细胞生长因子以牛血清白蛋白作联接包裹在聚乳酸-羟基乙酸共聚物内制成纳米微囊,根据公式计算微囊成球率、载药量及包封率;将微囊溶解于二氯甲烷中,进行体外释放实验检测不同时间牛血清白蛋白吸光度,作出牛血清白蛋白释放曲线;将角质细胞生长因子纳米微囊交联于脱细胞真皮表面,制成荷载角质细胞生长因子纳米微囊脱细胞真皮(KGF-ADM),在扫描电镜下观察微囊形态、分布及其与脱细胞真皮连接情况;采用Ⅰ型胶原酶复合胰蛋白酶消化的方法,从门诊健康患者无菌手术切除的包皮组织中获取表皮细胞单细胞悬液,经免疫荧光检测,证实其中含表皮干细胞,将表皮干细胞群分别接种于KGF-ADM及聚乳酸-羟基乙酸共聚物上,于恒温箱中培养3d后,在扫描电镜下观察细胞形态、生长情况及其与材料连接情况。结果:①纳米微囊成球率为85%,载药量为17.3%,包封率为73.5%。②纳米微囊中牛血清白蛋白可以控制缓慢释放,其释放曲线显示初期释放速度较快(前5d累计释放约40%),后进入缓慢释放期(30d累计释放约75%)。③扫描电镜检测显示纳米微囊形态规则,在KGF-ADM表面分布均匀,与KGF-ADM联接良好,部分分布于KGF-ADM深面;表皮干细胞群在KGF-ADM上生长活跃,细胞形态良好,部分形成克隆。结论:采用该方法可成功构建荷载角质细胞生长因子纳米微囊的新型组织工程化皮肤。     

The binding of human alloantibodies to recombinant glycophorin A

Chinese hamster ovary (CHO) cells were transfected with the wild-type, M allele of glycophorin A cDNA. The binding of human alloantibodies to recombinant glycophorin A was assessed with a modified hemagglutination-inhibition assay. Patient sera were incubated with acetone powders derived from CHO cells, and the adsorbed supernatants were tested in standard hemagglutination assays. Five M antibodies and one sample containing anti-En(a) bound to transfected CHO cells expressing glycophorin A but did not bind to untransfected CHO cells. Three N antibodies as well as 21 other alloantibodies (representing other major red cell blood group specificities) bound to neither CHO cell line. The M allele specificity of recombinant glycophorin A was further verified by the demonstration that a high-titer D alloantibody maintained the same titer of agglutination after incubation with recombinant glycophorin A. Transfected CHO cells thus express an M blood group antigen that appears to be serologically equivalent to that found on human red cells. A panel of cell lines expressing mutant glycophorin A molecules with defined variations in amino acid sequence and carbohydrate composition will be useful in studies of the fine specificity of human glycophorin alloantibodies. This approach may also provide an abundant source of artificial antigens for clinical use in blood group serology.     

DOES THE METHOD OF TRANSLUMINAL CORONARY REVASCULARISATION INFLUENCE RE-STENOSIS? BALLOON ANGIOPLASTY,ATHERECTOMY AND STENTS COMPARED

SUMMARY Luminal renarrowing after successful coronary angioplasty is now recognised as a continuously distributed process which is determined largely by the extent of luminal increase achieved at angioplasty. In this study an alternative analytical approach is applied to determine whether luminal renarrowing following coronary intervention is related to the mechanism of luminal increase (ie by balloon, by atherectomy, by a self-expanding stainless steel mesh stent, or by a balloon-expandable tantalum coil stent). The results confirm the known proportional relationship between luminal renarrowing during follow-up and luminal improvement at intervention, regardless of the device used. However, significant differences were observed between the devices, which may reflect device-specific characteristics of the hyperplastic response to vessel injury and may have clinical implications.