Alpha-1-antitrypsin-human leukocyte elastase complexes in blood: quantification by an enzyme-linked differential antibody immunosorbent assay and comparison with alpha-2-plasmin inhibitor-plasmin complexes

An enzyme-linked immunosorbent assay (ELISA) has been developed for the quantification of alpha 1-antitrypsin-human leukocyte elastase (alpha 1AT-E) complexes. In the ELISA, the alpha 1AT-E complex is bound to a surface by rabbit antileukocyte elastase antibody, and the inhibitor- proteinase complex is quantified by a second antibody, rabbit anti- alpha 1-antitrypsin F(ab')2, labeled with alkaline phosphatase. alpha 1AT-E complexes were detected when a final concentration of 2.2 nmol/liter of leukocyte elastase was added to plasma. The concentration of these complexes increased with additional elastase. In clotting blood, alpha 1AT-E complexes were generated in parallel with the conversion of 125I-fibrinogen to fibrin, whereas alpha 2-plasmin inhibitor-plasmin (alpha 2PI-P) complexes were not formed. The concentration of alpha 1AT-E complexes in 19 of 21 controls was less than 2.2 nmol/liter. Patients with laboratory evidence for disseminated intravascular coagulation (DIC) demonstrated elevated alpha 2PI-P complexes with either increased or normal concentrations of alpha 1AT-E complexes. Patients without evidence for DIC, but who demonstrated prolonged reptilase clotting times, were studied. This group had increased alpha 1AT-E but normal alpha 2PI-P complex levels, raising the possibility that elastase release in vivo may be accompanied by limited degradation of fibrinogen. These assays thus serve as useful probes for the study of leukocyte activation and of the interactions between cellular and plasma proteolytic enzyme systems.     

A monoclonal antibody that inhibits activation of human Hageman factor (factor XII)

A monoclonal antibody to human Hageman factor (HF, factor XII) was derived from BALB/c mouse spleen cells fused with NS-1 mouse myeloma cells. This antibody, purified from ascites fluid, reacted with HF to inhibit the activation of HF, purified or in normal pooled plasma, as measured by a coagulation assay. The antibody did not inhibit the coagulant activity of activated HF. The antibody also inhibited the generation of amidolytic activity in HF-ellagic acid mixtures, but failed to inhibit the amidolytic properties of the carboxy-terminal fragment of HF (HFf). Amidolytic activity, absent in an HF-monoclonal antibody mixture, was generated upon treatment with insoluble trypsin. Monoclonal antibody, bound to CNBr Sepharose 4B gel (Pharmacia Fine Chemicals, Piscataway, NJ), reversibly bound HF in plasma or in buffer, without activating it. HF was then eluted with 4 mol/L guanidine HCI. The passage of 125I-labeled HF enzymatically cleaved by trypsin through a column of monoclonal antibody-CNBr Sepharose 4B gel resulted in flow- through of HFf with a molecular weight (mol wt) of 30,000 and HF fragments of mol wt 12,000. Elution with 4 mol/L guanidine HCI yielded several HF fragments (mol wt 80,000, 52,000, and 40,000) but not HFf. These data suggest that the single determinant recognized by the murine monoclonal antibody is not on HFf, but rather on the amino-terminal fragment thought to be involved in the binding activity of HF. The monoclonal anti-HF bound to CNBr-activated Sepharose 4B gel could be used to artificially deplete plasma samples of HF.     

Detection of rubella virus antibody by enzyme linked immunosorbent assay with parallel line method]

An attempt was made to measure the antibody to rubella virus in human sera by ELISA by calculating the relative potency by the method of the parallel line assay. As a standard serum, adult serum 8 months after rubella infection was used. Sample sera were collected from 42 infants before MMR vaccination and 8-10 weeks after the vaccination and 48 adults three years or more after rubella vaccination. In addition, three infant sera with rubella 6-19 days after onset of rash and three gamma immunoglobulin products were used. The dose response curve of the standard serum and that of the sample serum showed the lineality and the regression line of the sample serum was parallel to that of the standard serum. And the relative potency of sample sera was successfully calculated. The good correlation was observed between the rubella antibody titer by hemagglutination inhibition test and that measured by ELISA. The coefficients of variance of relative potency obtained from four repeated measurements for two weeks showed from 15% to 25% in four sera of HI high titer. The reproducibility of parallel line assay was also satisfactory.     

Enzyme linked immunosorbent assay: determination of anti-adenovirus antibodies in an infant population

In order to define an accurate assay for anti-adenovirus antibody detection, a recently developed ELISA was compared with IFA and CF. On 58 sera, the ELISA was more sensitive than both CF and IFA, which showed relative sensitivities of 63% and 94%, respectively. It was not possible to determine the exact specificity of the tests because of the lack of a gold standard. Furthermore, the ELISA was used to define the prevalence of adenovirus antibodies in 116 infants between 1 and 24 months old (mean 7.28). The data showed that maternal antibodies waned by the age of 5 to 6 months and that more than 80% of the children had been infected by adenoviruses by the age of 10 months.     

Quantification of soluble HLA class I gene products by an enzyme linked immunosorbent assay

Summary A simplified enzyme linked immunosorbent assay utilizing an HLA class I frameworkspecific monoclonal antibody and a polyclonal enzyme linked beta-2 microglobulin specific antiserum has been established for the quantitative measurement of soluble HLA class I molecules. A total of 219 unrelated healthy individuals and 137 members of 28 families typed for HLA were analyzed for their non-membrane bound, i.e. soluble HLA-A,B,C antigens (sHLA-A,B,C). As reported by others, we observed associations of higher or lower sHLA-A,B,C values to particular HLA antigens: High plasma values were observed in probands positive for HLA-A23, A24, A29, Aw33, Bw65, and Cw8 and low values in HLA-B27 and B37 positive individuals. However, as shown by family studies, levels of sHLA-A,B,C were apparently not controlled by the MHC haplotypes alone, since no significant difference between HLA identical siblings and two haplotype different individuals could be detected. Thus, additional non-MHC linked gene(s) may be involved in the release of class I gene products.Supported in part by a research grant from the Fresenius AG, Oberursel, Federal Republic of Germany     

Enzyme linked immunosorbent assay for the diagnosis of human neurocysticercosis: a preliminary report

The diagnostic efficacy of an indirect enzyme linked immunosorbent assay (ELISA) was evaluated in cases of neurocystecercosis. Subjects studied included 22 cases and 30 controls (comprising 12 cases of surgically confirmed hydatid disease, 5 cases each of tuberculoma and P.U.O. and 8 cases of pyogenic meningitis). A standard ELISA was performed using porcine cysticerci as antigen. Sensitivity and specificity of the test were calculated for serum and cerebrospinal fluid separately. The test was found to give a sensitivity of 68 and 33 per cent for serum and C.S.F. respectively. The specificity for confirmed case was found to be cent per cent for both with the criteria of reporting used. The sensitivity of the test may be increased by using purified specific antigen and/or sandwich ELISA instead of indirect ELISA technique.     

Quantitation and identification of human monocytic colony-stimulating factor in human serum by enzyme-linked immunosorbent assay

An enzyme-linked immunosorbent assay (ELISA) system for the quantitation of human monocytic colony-stimulating factor (hM-CSF) was established, which was based on the "dual antibody immunometric sandwich" principle using horse and rabbit polyvalent antibodies against human urinary colony-stimulating factor (CSF-HU). The minimal detectable level of hM-CSF was 10 U/mL, and the assays showed good reproducibility. As measured by this method, the average serum hM-CSF level of 20 normal adults was 540 +/- 110 U/mL (range, 300 to 800 U/mL). The peak of hM-CSF measured by ELISA was identical to that measured by bioassay when semipurified CSF-HU was fractionated by reversed-phase high performance liquid chromatography (HPLC). This method detected two types of hM-CSF, which had approximate molecular weights of 85 Kd (CSF-HU) and 45 Kd in human serum and urine; the ratio of 85:45 Kd was very high in serum and the amounts of the two types were nearly equal in urine. After anticancer chemotherapy, the serum hM- CSF level of one half of the patients with hematological malignancy was elevated according to the reduction in neutrophil number, while it was almost in the normal range in the other half of the patients, indicating the possibility that anticancer chemotherapy damaged the hM- CSF-producing cells. This ELISA method may be useful for monitoring the serum hM-CSF level after anticancer chemotherapy.     

Measurement of free, one-chain tissue-type plasminogen activator in human plasma with an enzyme-linked immunosorbent assay based on an active site-specific murine monoclonal antibody

An enzyme-linked immunosorbent assay for free tissue-type plasminogen activator (t-PA) in human blood was developed based on a murine monoclonal antibody directed against the active site of t-PA. The lower limit of sensitivity of the assay applied to plasma is 2 ng/mL for one-chain t-PA but only 100 ng/mL for two-chain t-PA. Free t-PA in plasma taken at rest was found in 6 of 21 healthy subjects (4.5 +/- 0.8 ng/mL, mean +/- SD) and increased to 14 +/- 7.0 ng/mL after venous occlusion in 18 of these individuals. A linear correlation between total t-PA and free t-PA was observed with r = 0.92 (n = 18) and a slope of 1.08, indicating that t-PA released from the vessel wall circulates in the blood as the one-chain form. In 16 of 18 patients with deep vein thrombosis, the increase of total t-PA antigen after venous occlusion was comparable to that observed in controls, but the free t-PA was significantly lower or undetectable. The present assay for free t-PA may be useful for the investigation of the release and inhibition of t-PA under physiological, pharmacological, or pathological conditions in humans.     

Detection of anti-pyruvate dehydrogenase complex antibody in primary biliary cirrhosis by an enzyme-linked immunosorbent assay

The methods to detect antimitochondrial antibodies (AMAs), which are characteristically positive in primary biliary cirrhosis (PBC), have some problems in technical difficulty, sensitivity and specificity. Based on the finding that one of the major antigens corresponding to AMAs was the E2 component of pyruvate dehydrogenase complex (PDH), a very simple enzyme-linked immunosorbent assay (ELISA) to detect anti-PDH antibody (anti-PDH) has been developed in this study. Among 68 patients with PBC, IgG class anti-PDH and IgM class anti-PDH were detected in 64 patients (94.1%) and in 55 patients (80.8%), respectively, while only three cases (4.4%) were both negative. Mean optical densities (O.D.) of sera from patients with PBC were 0.536±0.386 (mean±SD) in IgG class and 0.308±0.342 in IgM class. No positive cases were detected in the following patients by this ELISA: 20 patients with acute viral hepatitis, 24 with chronic persisitent hepatitis, 32 with chronic active hepatitis, 19 with liver cirrhosis, 19 with hepatocellular carcinoma, 19 with acute intrahepatic cholestasis, 10 with autoimmune hepatitis, and six with systemic lupus erythematosus. Among nine AMAs negative cases with PBC by conventional indirect immunofluorescence (IF) assay, seven cases were found to be positive by this ELISA. The inter-assay coefficient of the variation of this method ranged from 4.9% to 5.8% and the intra-assay coefficient of variation from 3.8% to 5.1%. Therefore, this ELISA is useful for diagnosis of PBC.     

Inhibition of the activation of Hageman factor (factor XII) by human vascular endothelial cell culture supernates.

The supernatant fluid (conditioned medium) of cultured human vascular endothelial cells inhibits activation of Hageman factor (factor XII), whether by ellagic acid, bovine brain sulfatides, or bismuth subgallate; inhibition appears to be a property of one or more proteins in the culture supernates. This phenomenon may contribute to maintaining the fluidity of circulating blood by inhibiting surface activation of the intrinsic pathway of coagulation.     

Utilization of a peroxidase antiperoxidase complex in an enzyme-linked immunosorbent assay of elastin-derived peptides in human plasma

Chronic obstructive pulmonary disease (COPD), a major cause of morbidity and death in the smoking population, develops insidiously over many years, and significant impairment of lung function usually occurs before the disease is diagnosed. Because lung elastin degradation appears to be a prerequisite for the development of the disease, immunologic detection of elastin-derived peptides in the blood might be an effective approach to the early detection and monitoring of the disease. We here report an improved enzyme-linked immunosorbent assay for elastin peptides using a peroxidase-antiperoxidase complex as the reporter group. The assay is sensitive to 2 ng/ml elastin peptides. We show that for optimal, reproducible results the assay should be carried out at 16 degrees C rather than at room temperature and that determinations should be made on plasma containing protease inhibitors rather than on serum. The levels of elastin-derived peptides appeared to remain relatively constant when multiple samples were taken during a 5- to 10-wk period from individual subjects. In addition, patients with COPD had elevated elastin peptide levels (127 +/- 47 ng/ml) compared with levels in normal nonsmokers (58 +/- 17 ng/ml), whereas normal smokers had values intermediate between the 2 groups (mean peptide levels of 76 +/- 42 ng/ml). A small group of normal smokers (20%) had elevated elastin peptide levels similar to those in the emphysema group and may represent that group of smokers who are at risk of developing obstructive lung disease.     

Determination of thrombin-hirudin complex in plasma with an enzyme-linked immunosorbent assay.

An enzyme-linked immunosorbent assay (ELISA) was developed for the determination of the thrombin-hirudin complex (TH) in plasma. The test is based on the sandwich principle and uses appropriate antibodies which selectively bind the corresponding moieties of the complex. The assay was calibrated by adding performed TH to normal human citrated plasma. The detection limit of the assay was 1.2 ng/ml. Mean coefficients of variation of 6.0% (intra-assay) and 6.4% (inter-assay) were found. The presence of TH was demonstrated in normal human plasma that was spiked with hirudin and subsequently activated in vitro by calcium-thromboplastin to generate thrombin. This complex was also found in plasma samples from pigs which had been treated with hirudin during experimentally induced septicaemia.     

In vitro activation of the contact (Hageman factor) system of plasma by heparin and chondroitin sulfate E

A large number of negatively charged macromolecules, including DNA, glycosaminoglycans, and proteoglycans, were tested as possible activators of the contact (Hageman factor) system in vitro. Activation was assessed by conversion of prekallikrein to kallikrein, as determined by amidolytic assay and by cleavage of 125I-Hageman factor into 52,000- and 28,000-dalton fragments. Of particular interest to these studies, heparin proteoglycan and glycosaminoglycan from rat peritoneal mast cells, and squid chondroitin sulfate E, which is representative of the glycosaminoglycan from cultured mouse bone marrow derived mast cells, induced the reciprocal activation between Hageman factor and prekallikrein. In addition, naturally occurring heparin glycosaminoglycans from pig mucosa, bovine lung, and rat mast cells also induced activation. In contrast, native connective tissue matrix glycosaminoglycans and proteoglycans from several sources were inactive, although when one such chondroitin sulfate was further sulfated in vitro, it gained activity. When the negative charge of the activating agents was blocked by the addition of hexadimethrine bromide, the cleavage of 125I-Hageman factor in the presence of prekallikrein was prevented. The active negatively charged macromolecules induced cleavage of 125I-high molecular weight kininogen in normal plasma but not in Hageman factor-deficient or prekallikrein- deficient plasmas. Reconstitution of prekallikrein-deficient plasma with purified prekallikrein restored the kininogen cleavage upon addition of the active proteoglycans. These results suggest that both heparin from connective tissue mast cells and highly sulfated chondroitin sulfate E from cultured mouse bone marrow derived mast cells (which are considered synonomous with mucosal mast cells) could activate the contact system of plasma subsequent to an activation secretion response.     

Inactivation of factor XIa in human plasma assessed by measuring factor XIa-protease inhibitor complexes: major role for C1-inhibitor

From experiments with purified proteins, it has been concluded that factor XIa (FXIa) is inhibited in plasma mainly by alpha 1-antitrypsin (a1AT), followed by antithrombin III (ATIII), C1-inhibitor (C1Inh), and alpha 2-antiplasmin (a2AP). However, the validity of this concept has never been studied in plasma. We established the relative contribution of different inhibitors to the inactivation of FXIa in human plasma, using enzyme-linked immunosorbent assays (ELISAs) for the quantification of complexes of FXIa with a1AT, C1Inh, a2AP, and ATIII. We found that 47% of FXIa added to plasma formed complexes with C1Inh, 24.5% with a2AP, 23.5% with a1AT, and 5% with ATIII. The distribution of FXIa between these inhibitors in plasma was independent of whether FXIa was added to plasma, or was activated endogenously by kaolin, celite, or glass. However, in the presence of heparin (1 or 50 U/mL), C1Inh appeared to be the major inhibitor of FXIa, followed by ATIII. Furthermore, at lower temperatures, less FXIa-C1Inh and FXIa-a1AT complexes but more FXIa-a2AP complexes were formed. These data demonstrate that the contribution of the different inhibitors to inactivation of FXIa in plasma may vary, but C1Inh is the principal inhibitor under most conditions.     

Assessment of diagnostic enzyme-linked immunosorbent assay kit and serological markers in human brucellosis

This study was performed to evaluate commercial brucella immunoglobulin G and M enzyme-linked immunosorbent assay (IgG and IgM ELISA) kits for the diagnosis of human brucellosis and to suggest a candidate prognostic marker for human brucellosis. We determined the serum levels of brucella IgG, IgM, C-reactive protein (CRP), soluble CD14 (sCD14), and neopterin in patients with brucellosis and compared them with those of normal healthy persons, patients with tuberculosis, and patients with other diseases. It was found that the sensitivity of ELISA to diagnose brucellosis was high when both IgG and IgM ELISA were used together. This study showed that serum CRP, sCD14, or neopterin levels were significantly high during the course of human brucellosis. The above markers, alone or in combination, might have the potential to evaluate treatment outcomes in human brucellosis. The markers that can predict the variability of agglutination titer was also determined. It was found that the titer value alone does not fully represent disease status.     

Detection of antigens of Mycobacterium tuberculosis in patients of infertility by monoclonal antibody based sandwiched enzyme linked immunosorbent assay (ELISA)

A sandwich ELISA to detect specific protein antigens of Mycobacterium tuberculosis was developed by using polyclonal anti-BCG rabbit antibodies as the primary capture antibodies. The mycobacterial antigens were detected with horseradish peroxidase conjugated monoclonal antibodies (P 6) as secondary antibodies. The enzyme was detected by using 1,2 Phenylenediamine dihydrochloride (OPD) and Hydrogen peroxide as substrate. The antigen could be quantitated through linear regression analysis with lower detection limit of 1.25 μg/ml. 50 consecutive cases of infertility were examined by laparoscopy and tested for the presence of the antigen in the serum. Mycobacterial antigen could be detected in 9 of the 12 cases with definitive diagnosis of tuberculosis, 5 of the 23 where the diagnosis of tuberculosis was probable and in only 1 of 15 patients who had no laparoscopic abnormalities indicative of tuberculosis.     

Measurement of factor VIII procoagulant antigen in normal subjects and in hemophilia A patients by an immunoradiometric assay and by an enzyme-linked immunosorbent assay

Factor VIII coagulant antigen (FVIII:Ag) and FVIII coagulant activity (FVIII:C) were measured in 102 healthy individuals, in 5 hemophilia A carriers and in 21 hemophilia A patients before and after infusion of heat-treated high-purity FVIII concentrates. Factor VIII:Ag was determined by a solid-phase micro enzyme-linked immunosorbent assay (ELISA) using monoclonal antibodies and by a conventional solid-phase immunoradiometric assay (IRMA). Factor VIII:C was assessed using a one-stage assay. The micro ELISA was decidedly more precise than the IRMA. There was a close correlation between the results obtained by the three assays in the plasma of healthy subjects and in hemophilia A carriers. After transfusion of FVIII concentrates to hemophilia A patients, the FVIII:Ag recoveries were significantly lower than the FVIII:C recoveries and the biological half-life of FVIII:Ag was significantly shorter than for FVIII:C. The calculated half-life of FVIII:C was longer than in any previous study.     

Development of an enzyme linked immunosorbent assay for fast screening of cimaterol residues in various matrices

IntroductionInterest in methods to improve the efficiency of animal production has focused on betaadregenic agonists such as cimaterol in recent years. Cimaterol has been recognised as a repartitioning agent that improves carcass composition by increasing muscle deposition and reducing fat. It also has the ability to accelerate livestock growth. In human however, they are generally used as anti-asthmatic agent. Therefore, excess cimaterol residues in livestock products may pose a genuine risk for human health. This has led to the prohibition of cimaterol usage in every stage of food production. To know whether food matrices contain cimaterol residue, one must need to test it.ObjectiveTo develop a sensitive and specific Enzyme-linked Immunosorbent Assay (ELISA) for the detection of cimaterol in various matrices.MethodsThe antiserum was raised in rabbits, employing cimaterol-diazo-BSA (CIM-BSA) as antigen. The ELISA test is a solid phase direct competitive assay using horseradish peroxidase conjugate as the competing entity. The total incubation time of the assay is 45 minutes.Results & DiscussionThe concentration of cimaterol to decrease tracer binding by 50% (IC50 value) in a direct competitive ELISA method was found to be 2.9ng/mL. The antibody is specific with low crossreactivity towards other beta-agonists tested such as propanolol (11.7%), clenbuterol (11.4%), mapenterol (7.3%), metoprolol (5.3%), and atenolol (4.6%). The antibody has cross-reactivity of < 1% to other drugs such as terbutaline, ractopamine, timolol and isoxsuprine. The limits of detection (LOD) of the ELISAfor swine urine, chicken muscle, shrimp tissue, milk and animal feed were determined as 0.33 ng/mL, 0.30 ng/mL, 0.30 ng/mL,1.18ng/mL, and 0.28 ng/mL respectively.ConclusionA sensitive and specific ELISA was developed to detect the beta 2-adregenic agonist cimaterol in various matrices such as urine (swine), muscle (chicken), tissue (shrimp), milk and animal feed.     

双单克隆抗体夹心酶联免疫吸附试验检测鼠疫F1抗原的实验观察

目的 观察双单克隆抗体(F1-McAb)夹心酶联免疫试验(DMcAbS-ELISA)快速检测鼠疫F1抗原的敏感性和特异性.方法 采用鼠疫细菌学检验、DMcAbS-ELISA和反向间接血球凝集试验(RIHA)对比检测鼠疫感染鼠和阴性对照鼠脏器标本.结果 共检测225份阴性对照鼠脏器标本,鼠疫细菌学检验、DMcAbS-ELISA和RIHA法检测F1抗原均为阴性.共检测308只鼠疫感染鼠脏器标本,鼠疫细菌学检验、DMcAbS-ELISA、RIHA法阳性率分别为92.21％(284/308)、90.91％(280/308)和89.61％(276/308),3种方法比较,差异无统计学意义(x2=5.65,P＞0.05).DMcAbS-ELISA法与鼠疫细菌学检验结果符合率为97.00％[(274+243)/533],Kappa值为0.940;与RIHA法符合率为99.25％[(276+253)/533],Kappa值为0.985.脏器标本F1抗原检测的真实性比较:DMcAbS-ELISA法敏感性为96.48％(274/284),特异性为97.59％(243/249),阳性预测值为97.86％(274/280),阴性预测值为96.05％(243/253),一致性为96.99％11/4×(274/280+274/284+ 243/253+243/249)|,Youden指数为0.9407;RIHA法的敏感性为96.13％(273/284),特异性为98.80％(246/249),阳性预测值为98.91％(273/276),阴性预测值为95.72％(246/257),一致性为97.39％[1/4×(273/276+273/284+246/257+246/249)],Youden指数为0.9492.DMcAbS-ELISA法对鼠疫菌检测灵敏度为2.7×104cfu/ml,RIHA法为2.2×105 cfu/ml;两种方法检测F1抗原灵敏度均为10 μg/L.结论 DMcAbS-ELISA法检测鼠疫F1抗原具有敏感、特异、简便、快速的特点,是有应用价值的鼠疫快速诊断技术.