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Human antibodies to immunoglobulin A (IgA). A radioimmunological method for differentiation between anti-IgA antibodies and IgA in the serum of IgA deficient individuals.

In the sera of 12 out of 27 individuals with IgA deficiency (serum level below 0.02 mg IgA/ml) class-specific anti-IgA antibodies were demonstrated by haemagglutination. These sera showed false-positive results in a solid-phase inhibition radioimmunoassay (RIST) (apparent IgA concentration between 0.6 and 13.7 microgram IgA/ml) indicating that the RIST is not an appropriate test for the analysis of serum of IgA deficient individuals. A modification of the RIST is proposed (titration RIA) that permits differentiation between low levels of IgA and class-specific anti-IgA antibodies. With this test IgA deficient individuals could be classified as those with low but detectable levels of IgA and those with class-specific anti-IgA antibodies. A computer procedure was developed to calculate both the amount and the avidity (K) of the anti-IgA antibodies and to simulate the assay system. The K value calculated from experimental points proved to be an overestimation of the K value which fitted most adequately in the simulation. The comparison of the results with clinical findings indicated a possible correlation between the amount and the avidity of the anti-IgA antibodies and the appearance of anaphylactic reactions after transfusion of IgA.

Antibodies↗

Immunoradiometric assay for cytomegalovirus-specific IgG antibodies: assay development and evaluation in blood transfusion practice.

An immunoradiometric assay (radio-immunosorbent test; RIST) for the detection of IgG antibodies to human herpesvirus 4 [human cytomegalovirus (CMV)] has been developed. The technique utilizes CMV antigen passively adsorbed to a polyvinyl microtitration plate and a radiolabelled murine monoclonal anti-human IgG antibody to detect binding of human antibody to the 'solid phase' reagent. The assay was optimized, and its specificity confirmed by testing paired acute and convalescent sera from patients with acute CMV or other human herpesvirus infections. To determine the assay's sensitivity 1433 blood donor sera were examined. The RIST was more sensitive than a standard complement fixation (CFT), in that 53% of these sera were positive by RIST and 48% positive by CFT. There were 1303 concordant results, 88 sera positive only by RIST and 19 sera were only positive by CFT. These discrepant results remained after an attempt to exclude false positive reactivity; their significance is discussed. Use of a monoclonal anti-human IgG antibody in the RIST reduced non-specific binding to the control uninfected cell antigen such that blood donor sera could be tested in the assay using only a CMV antigen without generating an unacceptable false positive rate.

Animals↗

[How to define the normal level of serum IgE in adults?].

Variations in the upper limit of normal total serum IgE have been reported: they can range from 150 to 1,000 UI/ml; but the usually accepted upper limit is between 150 and 300 UI/ml. In this study we measured the total serum IgE levels (RIST-Pharmacia) in 69 randomly selected control subjects; 38 had no previous history of atopic or parasitic disease. The normal values observed were 7-460 UI/ml for the whole of the control group (10th-90th percentiles) and 0.5-540 UI/ml for the 38 selected subjects (5th-95th percentiles). Logarithmic conversion is compulsory in order to obtain a gaussian distribution. This enables 80 p. 100 of the control subjects to be grouped within 4-450 UI/ml or 90 p. 100 of the selected subgroup within the range of 1.5-677 UI/ml. As many allergic patients have a normal serum IgE level and a number of non-allergic diseases may be associated with an increased serum IgE level, the diagnostic importance of this investigation is limited. The cost-effectiveness is very low and raises the problem of using this test in everyday practice.

Adult↗

[Radioimmunological estimation of digoxin in urine (author's transl)].

When separating free and antibody bound digoxin, dextrancoated charcoal suspensions in protein-free urine dilutions develop an improve sieve effect which improves with aging of the suspensions. On addition of albumin to the dilution medium (buffer), the adsorptive capacities become stabilized. In urine dilutions less than of 1:50, false positive digoxin concentrations were measured. Determinations of 0-5 ng digoxin/ml in the diluted urine (1:100) and in the buffer solution show identical results. The recovery of added digoxin (1 ng and 2 ng/ml) is 100%; the lower detection limit is 3.6 mug/l urine. Between-assay variation for means of duplicates shows in the main measuring range (1.5-2.8 ng digoxin/ml) a variation coefficient less than of 4.5%; for a commercial test this value is distinctly higher. Dihydrodigoxin is measured at 3% only. Application of this method for measuring cumulative glycoside elimination of 5 healthy persons (0.5 mg digoxin daily intravenously during 2 weeks) results in a minimal interindividual variation of 5.1%. In a test preparation with a bioavailability of 94.6% the variation is 5.2%.

Biological Availability↗

Optimum conditions for the radioimmunoprecipitation assay for the major internal protein of bovine leukemia virus.

The sensitivity of the radioimmunoprecipitation assay for the major internal protein (p24) of bovine leukemia virus (BLV) was examined. Conditions were varied for the assay by 1) using larger amounts of serum and 2) increasing the amount of second antibody. Sensitivity for the p24 radioimmunoprecipitation test was greatest when 10 microliter of test serum and 200 microliter of rabbit anti-bovine IgG were used. Under these conditions there were no discrepancies between the p24 radioimmunoprecipitation test and the radioimmunoprecipitation test for the surface glycoprotein (gp51) in 380 cattle from commercial dairy herds.

Animals↗

[Allergologic explorations in children].

Guidelines to the multitude of allergologic tests are defined. But, in practical experience, skin prick test are the first and the best test for allergy diagnosis. Positive skin prick test refer to sensitization in accordance with clinical history.

Adolescent↗

Sensitive thyroid-stimulating hormone assays: clinical applications and limitations.

Sensitive TSH assays have important applications in various conditions, including the diagnosis of hypothyroidism and hyperthyroidism, monitoring thyroid hormone therapy and treated thyrotoxic patients, and evaluating thyroid dysfunction in nonthyroidal illnesses and pregnancy. Interpretation of the TSH value should be made with a clear understanding of its limitations. TSH may be inappropriately secreted by pituitary tumors and by pituitary dysfunction due to thyroxine resistance. At present, it is uncertain whether clinically euthyroid patients with autonomously functioning thyroid nodules, or with multinodular goiters, or patients taking thyroid hormone who have suppressed TSH values, are actually euthyroid at a cellular level. Other factors that affect TSH levels are the biologic variation in its secretion, the presence of heterophilic antibodies in a patient's serum, and various drugs. But perhaps the most important factor affecting the TSH assay is severe nonthyroidal illness in hospitalized patients. The new ultrasensitive TSH assay does not yet replace other thyroid function tests, but it is clearly emerging as an important means of screening patients for thyroid dysfunction, especially ambulatory patients without other serious illnesses. It can usually separate patients with thyroid dysfunction from euthyroid individuals. Good clinical assessment is always necessary, and other thyroid function tests are often needed. The sensitivity of these new TSH assays in the diagnosis of thyrotoxicosis and hypothyroidism is excellent; the specificity is not as good. Nonetheless, at present this test can be used in the initial diagnosis of thyroid dysfunction as outlined in Figure 2.(ABSTRACT TRUNCATED AT 250 WORDS)

Female↗

[Recent progress in immunologic technics for the diagnosis of systemic mycoses].

The new immunological techniques used for the diagnosis of systemic mycoses are very specific. Purified antigens are now available and new methods allow the detection of various classes of specific antibodies. Precipitation tests, such as bidimensional electrophoresis and electroimmunodiffusion, are compared with passive agglutination tests; radioimmunoassay and enzyme immunoassays are analyzed. The value and utilization of cellular immunity and various other tests are discussed.

Agglutination Tests↗

Nonimmune complexes of pregnancy-specific beta 1-glycoprotein explain its heterogeneity.

Nonimmune complexes of pregnancy-specific beta 1-glycoprotein (SP1) explain its heterogeneity. Two proteins reacting with antisera specific to pregnancy-specific beta 1-glycoprotein (SP1) have previously been detected in serum from pregnant women by use of crossed immunoelectrophoresis (CIE). The major SP1-reactive protein, SP1 beta, has a molecular weight of about 90,000 and the minor, antigenically deficient protein, SP1 alpha, about 200,000. In this study, gel filtration of serum on Ultrogel AcA 34 and Sephacryl S-300 has revealed that classical radioimmunoassay (RIA) techniques of two types only measure SP1 beta. With RIAs specially designed to detect complexed SP1 two higher molecular weight, SP1-containing complexes could be identified. CIE of serum or fractions from gel filtrations revealed a loss of the anodal part of the SP1 precipitate. However, when 4% polyethylene glycol (PEG) was incorporated in the anti-SP1-containing gel an antigenically deficient precipitate developed in the alpha-region. Incorporation of antialbumin in an intermediate gel in CIE reduced the anodal loss of the SP1 precipitate in anti-SP1-containing gels without PEG which resulted in a homogeneous peak. In addition, in anti-SP1-containing gels with PEG the anodal precipitate was reduced. This SP1-albumin complex fulfills all criteria for the previously described SP1 alpha. For measuring low levels of SP1 RIAs can be used. For higher values nephelometry is preferable. Although the amount of complexed SP1 is small in comparison with the amount of native SP1 methods employing electrophoresis are not recommended. In such tests SP1 complexed to fast-moving proteins like albumin might influence the results.

Antigen-Antibody Complex↗

[Total serum IgE: normal pediatric values using the FAST IgE fluoroimmunoenzymatic technic].

This reports covers the application to paediatrics of total IgE determination by the means of a new direct, sandwich type, fluorescence enzyme immuno-assay (Fluoro-allergo sorbent test:FAST IgE). The technical process is adapted for usual determinations, in case of infants and young children, of low normal rates with a good sensitivity, and of high pathological rates. IgE total usual values are established by the FAST IgE test from serums of healthy children, aged from one day to 14 years. Seven age groups are to be distinguished.

Adolescent↗

New radioimmunoadsorbent method for detection of hepatitis B surface antigen.

A radioimmunoadsorbent assay for the detection of hepatitis B surface antigen (HBsAG) is described. The method uses small DEAE-cellulose columns to adsorb HBsAg from serum or plasma samples, and it uses 125 I-labeled antibody to HBsAg to detect the adsorbed antigen. A single 2-h incubation at 45 degrees C is used in the procedure. The sensitivity of the method was determined with the Bureau of Biologics HBsAg reference panels and was shown to be equivalent to other third-generation test methods. The specificity of the method was evaluated by testing specimens from blood donors, dialysis patients, and hospital staff in parallel with commercial radioimmunoassay kits for HBsAg. In the tests performed on 2,868 blood donor specimens, 6 positive specimens were identified by both the radioimmunoadsorbent method and the commercial radioimmunoassay kits. These positive specimens were confirmed by a counterimmunoelectrophoresis procedure. One nonconfirmable, repeatably positive specimen was observed with the radioimmunoadsorbent method. In testing 1,250 specimens from dialysis patients and hospital staff, 120 confirmable positive specimens were identified by both the radioimmunoadsorbent method and a commercial test. Overall, the false positive rate for the radioimmunoadsorbent method was found to be less than 1%.

Antigen-Antibody Complex↗

[Measurement of human tetanus antitoxin using as enzyme-linked immunosorbent assay].

An enzyme-linked immunosorbent assay (ELISA) has been developed for the detection and measurement of human tetanus antitoxin. This simple test has proved to be a simple and sensitive as the radio immunosorbent test (RIST) described earlier by the authors and needs no special equipment. The technique which is based on the pioneer work done by Eva Engvall, is described. The antitoxin titers obtained with ELISA and RIST are comparable.

Antibody Formation↗

Methods of quantifying circulating IgE.

Four radioimmunoassay techniques, two conventional and two sandwich, have been used to measure circulating IgE levels in 100 sera. The test sera had IgE levels ranging from 1.0 to 20,000 u/ml, and each was measured at five dilutions, ranging from three-fold to 400-fold. The same IgE standards were used throughout, and the optimal range for each assay was determined by assessing data for quality control sera and the WHO standard 69/204. To be of general use in the United Kingdom an IgE test must measure accurately levels as low as 20-30 u IgE/ml. The Phadebas RIST method failed to meet this criterion, and of the remaining tests the double antibody method had the most useful operating range and produced the most reliable results. However, the double antibody method is not available commercially and so, for the majority of laboratories, the Phadebas PRIST technique should be the method chosen.

Animals↗

[Diagnosis of type I hypersensitivity by laboratory test].

Type I hypersensitivity is a major problem in public health, often requiring numerous investigations which aim to diagnose atopy and identify the causative allergen. Among these investigations, several blood tests, mostly using immunoenzymatic methods, can be performed to measure total and specific IgE levels. Type I hypersensitivity can also be investigated with assays which quantitate several mediators released after cellular activation induced by allergens.

Adult↗

Quantitation of serum immunoglobulins.

This article reviews critically the current "state of the art" in the quantitation of immunoglobulins in serum and other body fluids. The methodologies reviewed include (a) those occurring in solution, for example, automated immunoprecipitin and laser nephelometric techniques, rate analysis techniques and radioimmunoassays; (b) techniques involving radial diffusion in agarose gels, with and without secondary development steps; and (c) those techniques involving solid supports, such as fluoroimmunometric assays and solid phase radioimmunoassays. The theory of each technique is presented with an analysis of the strengths and weaknesses, particularly sources of error, and the techniques are compared in terms of accuracy, precision, sensitivity, test cost, equipment cost, feasibility for use in different laboratory settings, and ease of handling. Problems associated with the antisera used, with standards, and with quality controls are discussed and solutions suggested.

Analysis of Variance↗