Rapid, simple and sensitive antigen capture ELISA for the quantitation of myoglobin using monoclonal antibodies

Novel, high incidence exercise-induced muscle bleeding model in hemophilia B mice: rationale, development and prophylactic intervention

INTRODUCTION

Muscle hematomas are the second most common complication of hemophilia and insufficient treatment may result in serious and even life-threatening complications. Hemophilic dogs and rats do experience spontaneous muscle bleeding, but currently, no experimental animal model is available specifically investigating spontaneous muscle bleeds in a hemophilic setting.

AIM

The objective of this study was to develop a model of spontaneous muscle bleeds in hemophilia B mice. We hypothesized that treadmill exercise would induce muscle bleeds in hemophilia B mice but not in normal non-hemophilic mice and that treatment with recombinant factor IX (rFIX) before treadmill exercise could prevent the occurrence of pathology.

METHODS

A total of 203 mice (123 F9-KO and 80 C57BL/6NTac) were included in three separate studies: (i) the model implementation study investigating the bleeding pattern in hemophilia B mice after treadmill exercise; (ii) a study evaluating the pharmacokinetics of recombinant FIX (rFIX) in hemophilia B mice and based on these data; (iii) the treatment study, which tested therapeutic intervention with rFIX. At termination of the treadmill studies the presence of bleeds was evaluated.

RESULTS

Treadmill exercise resulted in a high incidence of muscle bleeds in F9-KO mice but not in C57BL/6NTac mice. Treating hemophilia B mice with rFIX before treadmill exercise prevented muscle bleeds.

CONCLUSION

A novel model of muscle bleeds in hemophilia B mice, responsive to rFIX, has been developed.

Synergistic effects in antigen capture ELISA using three monoclonal antibodies directed at different epitopes of the same antigen

Using a panel of monoclonal antibodies (mAb) against human myoglobin (Mb), we have shown that the sensitivity of antigen-capture enzyme-linked immunosorbent assay (ELISA) may be significantly increased by the simultaneous immobilization on a solid phase of two co-operating capture mAbs. This method ("a three-site ELISA") uses three mAbs at different epitopes of the same antigen (two capture/one tracer), unlike the traditional two-site assay, using one capture and one tracer mAbs. We established two-site and three-site ELISA assays for Mb, by varying capture and tracer mAbs. Three-site assays showed 4-6 fold increase in sensitivity, if compared with two-site assays. The model for the effect has been suggested, according to which in three-site ELISA the high-affinity cyclic configurations may be formed by an antigen, two-capture mAbs and the surface of solid phase.

Cardiac myofibrillar proteins: biochemical markers to estimate myocardial injury

Ischaemic heart disease represents the most common of the serious health problems in the contemporary society and acute myocardial infarction (AMI) is the major cause of cardiovascular morbidity and death. The accurate localization and determination of the infarct size and the volume of myocardium at risk at the time of insult is crucial and vital for the choice of treatment. Initially the ischaemic cells are reversibly injured. However, if these changes are not reverted at the earliest, it results in the death of the myocyte. This irreversible myocyte necrosis travels transmurally towards epicardium in the form of a wavefront. A timely intervention during evolving infarct could reduce and delimit the infarct and preserve the left ventricular function. Enzyme analysis and electrocardiography (ECG) along with the clinical history of the patient is still considered to constitute a reliable triad in the diagnosis of myocardial infarction (MI). Efforts have been made to relate infarct size with the serum enzyme level changes without much success. In addition, a number of specialist techniques such as planar radioisotope imaging, single photon emission computed tomography (SPECT), positron emission tomography (PET), Echocardiography, Ventriculography and nuclear magnetic resonance (NMR) imaging have been devised to support diagnosis in the patients who show ambiguous symptoms and ECG findings. However most of these procedures are unavailable to the patients due to economic reasons while others have suffered due to non-availability of ideal radiopharmaceuticals. Major advances have been made in the methods based on immunological techniques to improve the detection and estimation of infarct. These methods are exclusively based upon the production and availability of specific antibodies against intracellular, cardiac specific components.

Qualitative bedside assay of increased human serum myoglobin by sandwich dot-immunogold filtration for the diagnosis of acute myocardial infarction

We isolated and purified myoglobin (MYO) from human fresh skeletal muscle and prepared monoclonal and polyclonal antibody from it. A sandwich dot-immunogold filtration assay (DIGFA) for the detection of MYO was developed by using affinity purified sheep anti-MYO antibody as the first antibody for coating nitrocellulose membranes (NCMs; the support) and colloidal gold labelled monoclonal antibody (H3) as the second antibody (an indicator). The test can be completed in 3 min without incubation or any equipment. A reddish dot, indicating positivity, is obvious to the naked eye. No interferences from bilirubin, hemoglobin, rheumatoid factors and lipid were found. In order to use undiluted serum, the detection limit was set at 100 microg of MYO/l. Concentrations up to 30,000 microg/l can be measured without getting a "hook" effect. Serum MYO levels in 53 patients with acute myocardial infarction (AMI), 100 healthy individuals, seven patients with chest pain but without myocardial ischemia and in 39 patients with renal insufficiency were measured simultaneously by DIGFA and enzyme-linked immunosorbent assay (ELISA). All serum samples from patients had MYO concentrations above 100 microg/l by ELISA and were positive by DIGFA. Serum creatinine values were related to MYO test results. Healthy individuals had MYO levels below 85 microg/l by ELISA and were negative by DIGFA.

Epitopic analysis and quantification of bovine myoglobin with monoclonal antibodies

Seven rat monoclonal antibodies (MAb) for bovine myoglobin were produced. Five antibodies reacted with surface-absorbed myoglobin whereas the two remainders reacted only in a sandwich type ELISA. The ability of different antibodies to bind simultaneously to myoglobin was examined by competition and additivity experiments and three noncompeting epitope regions were found. A two-site enzyme immunoassay was developed and allowed quantification of 30 ng/ml bovine myoglobin. These antibodies should be valuable tools in comparative studies for immunological reactivity of mammalian myoglobins and for myoglobin measurement in serum and urine of myopathic animals.

FPLC purification of mouse monoclonal antibodies from ascitic fluid using blue DEAE and thiophilic sorbents

Two fast methods for the purification of mouse monoclonal antibodies from ascites, fluids using Blue-DEAE and 'thiophilic' adsorbent (T gel) in the FPLC system are described. Blue-DEAE chromatography is useful only for IgG1, IgG2a and IgG2b monoclonal antibody purification. T gel is a satisfactory adsorbent for IgG2b purification. Other IgG subclasses and IgM can also be obtained by simple one-step procedures, but the preparations contain small amount of high molecular weight contaminants.