A nylon ball solid-phase radioimmunoassay for specific antibodies in human sera. Application to measurement of IgG antibodies to pollen allergens

Evidence of a common regulation of IgE and IgG-subclass antibodies in humans during immunotherapy

Based on a 3-year prospective study of 20 pollen-allergic patients, where a detailed analysis of the IgE, IgG1 and IgG4 immune response was performed, we propose that a common regulatory mechanism exists between the IgE and IgG1 synthesis and between IgE and IgG4 synthesis during immunotherapy. It was found that the IgE immune response to a number of antigens was quantitatively diminished during the period of immunotherapy when IgG1 was present early (week 12), and for other antigens there was a rise in IgE without an early IgG1 antibody response. Additionally, it was found that for some antigens a rise in IgE antibodies was contrasted by a fall in the IgG4 antibody response and for other antigens the opposite was true, indicating a regulatory mechanism between the IgE and the IgG4 synthesis. A statistical analysis showed that these findings were statistically significant at the 0.01% level for the IgE/IgG1 relationship and at the 0.05% level for the IgE/IgG4 relationship. These findings could have implications for future immunotherapy regimens.

Purification of Phleum pratense pollen extract by immunoaffinity chromatography and high-performance ion-exchange chromatography

Basic allergens of Phleum pratense pollen extract have been purified by either sequence gel filtration-ion-exchange high-performance liquid chromatography (HPIEX) and size-exclusion HPLC or sequence gel filtration-immunoaffinity chromatography and HPIEX. The second procedure seems to be suitable for preparative purposes.

A computational approach to the description of individual immune responses. IgE and IgG-subclass allergen-specific antibodies formed during immunotherapy

Detailed evaluation of the IgE and IgG-subclass immune response during immunotherapy can now be performed by crossed radio immunoelectrophoresis (CRIE). Some new concepts are introduced facilitating the handling of the vast amount of data obtained by quantitating the immune response. These concepts are "distance" between antibody responses and "immune response width". The 20 patients included in this study were pollen-allergic patients who underwent specific immunotherapy in a 3-year prospective study. It was found that the immune response during immunotherapy was restricted to IgG1 and IgG4 antibodies. The semi-quantitative CRIE analysis correlated with the RAST analysis for the IgE samples before start of immunotherapy, for the IgG1 samples at week 12, and for all the IgG4 samples. During immunotherapy the number of IgG1 antibodies directed to the different antigens increased towards 11 antigens and decreased towards six. For the IgG4 antibodies the number of reactions increased towards 15 antigens and decreased towards four. The increase is generally paralleled by an increase in quantitative immune response as well. For some of the antigens a rise in the IgE antibodies is contrasted by a fall in the IgG4 antibody response, and for other antigens the opposite was true, indicating a regulatory mechanism between the IgE and the IgG4 synthesis. The IgE immune response to a number of antigens, including the major allergens before the start of immunotherapy, was quantitatively diminished during the period of immunotherapy when IgG1 was present early (week 12) in the period, and for other antigens there was a rise in IgE without an early IgG1 antibody response. This suggests that IgG1 can have a regulating influence on the IgE synthesis. Finally, we have found that IgE antibodies with specificities not present in the samples taken before immunotherapy were formed during immunotherapy. These new IgE antibodies do not, however, seem to impair the outcome of treatment.

Immunochemical estimations of allergenic activities from outdoor aero-allergens, collected by a high-volume air sampler

To quantify airborne allergens in amorphus and morphological particles, a survey with collection of aero-allergens on glass fibre filters by means of a high-volume air-sampler (HIVOL) was conducted. In preliminary laboratory experiments we compared various filter elution techniques, and the pulverizing elution technique was found to be optimal with regard to yield and convenience. When a surfactant, Tween 20 (0.5% v/v), was added to the elution buffer, a recovery of 80% could be obtained. Allergens in eluates were analysed by means of an IgG-subclass RAST inhibition assay. This immunochemical method for quantification of airborne allergens was validated, as a high recovery of timothy grass pollen allergens was eluted from air filters, and eluates were shown specific by RAST inhibition. The amount of immunochemically measured airborne timothy and birch allergens collected by means of the HIVOL sampler was highly correlated with pollen counts obtained with a Burkard sampler (pollen trap) situated in the same place.

Image processing and pattern recognition algorithms for evaluation of crossed immunoelectrophoretic patterns (crossed radioimmunoelectrophoresis analysis manager; CREAM)

A computerized method for automatic evaluation and comparison of crossed immunoelectrophoretic and crossed radioimmunoelectrophoretic patterns that requires limited hardware resources has been developed. For the initial reading of the plates an ordinary video camera is used. Feature extractors that allow the computer to recognize a point on the precipitation curve as being a peak point have been developed. After this automatic procedure the program allows for an interactive menu-driven proofreading phase during which it is possible to force the system to take into consideration any number of extra points along the precipitation curve in the curve-fitting process. The system has been tested on crossed immunoelectrophoretic patterns as well as crossed radioimmunoelectrophoretic patterns and it has been shown that the system can recognize the same precipitation curves on different immunoplates and autoradiographs. In addition, the system reports the mean, the variance, and the area of the precipitation curves, thus allowing not only a qualitative comparison of two or more plates but also a quantitation of individual antigens or antibodies.

Treatment of hay fever with sodium cromoglycate, hyposensitization, or a combination

In 77 consecutive patients with grass pollen rhinitis as the only allergic disease, treatment with sodium cromoglycate (SCG) nasal spray, hyposensitization with aluminium hydroxide adsorbed extract of grass pollen as perennial treatment, and a combination of the two was compared. Specific serum-IgE, IgG and IgG4 were determined in patients who participated in three consecutive seasons. Significant immune response was found in the hyposensitization group, but not in the group treated with SCG. No correlation between the immunoglobulin responses and the individual symptom and/or medicine scores was found. Symptom and medicine scores were analysed in the 3 weeks with the highest pollen counts each year during 4 consecutive years. Higher scores were found in the group treated with sodium cromoglycate compared with the other two groups, but the difference was only significant for eye and total symptoms in the first season. None of the groups, however, suffered from more than mild to moderate symptoms even in the weeks with peak pollen counts. A significantly larger decrease in the wheals of the skin prick test was shown during hyposensitization than during treatment with SCG. No difference was found in the frequency of patients who became symptom-free or developed pollen asthma.

Methods for reducing non-specific antibody binding in enzyme-linked immunosorbent assays

Enzyme-linked immunosorbent assays were used to study (i) binding of rabbit antibodies (raised against litter mate liver plasma membrane fraction) to the immunizing membrane fraction, and (ii) binding of human antibodies to liver membrane fractions and to liver-specific lipoprotein (a liver membrane-derived antigen complex). When assays were conducted using the non-ionic detergent Tween 20 as blocking agent, high non-specific binding was encountered. With the low titre rabbit antisera high binding of non-immune test antibody and of second antibody (anti-rabbit IgG) to the immunogen, and also directly to the solid phase, was found. This was abolished by replacement of Tween 20 in the antibody diluent buffers by a non-reactive protein, casein proving to be a more effective blocking agent than either bovine serum albumin or gelatin. With human sera, high binding of human IgG to the solid phase was noted. This too was blocked by casein, but only when the anti-microbial agent Thimerosal was included in the casein buffer, and when Tween 20 in the wash buffer was replaced by casein-Thimerosal so that the solid phase was exposed to casein before incubation with the test serum. The casein buffers described may prove of general value in solid-phase assays where high non-specific binding is encountered.

Radioallergosorbent test (RAST) for measurement of IgG antibodies to Aspergillus fumigatus in sera of patients with different lung diseases

A radioallergosorbent test (RAST) for measuring human anti-Aspergillus fumigatus (Af) antibodies of the IgG class is described. The use of 125I-labelled animal antibodies against human IgG is compared with the use of 125I-labelled protein A. Under optimal conditions the radioactivity binding ratio between pooled patients' serum and pooled healthy persons' serum is 8-11.5. The immunoblotting technique was used to investigate so-called non-specific binding. The results obtained show that most if not all human sera contain anti-Af antibodies of the IgG type. The difference between pathological and normal immunological response to Af antigens seems to be in the antibody titres rather than in the presence or absence of antibodies to these antigens.

Characterization of IgG-subclass antibodies to individual allergens by crossed radioimmunoelectrophoresis

A crossed radioimmunoelectrophoretic (CRIE) method for detection of human IgG subclass specificities against individual antigens is described. After crossed immunoelectrophoresis (CIE) of the antigens the immunoplates are incubated with serum, washed and incubated with mouse monoclonal anti-human IgG-subclass antibodies. After washing, the plates are finally incubated with the 125I-labelled detector protein, rabbit anti-mouse IgG, and washed. The plates are then placed on an X-ray film for autoradiography. The specificity of the method was tested by inhibition with antigens in the first layer and by inhibition with myeloma sera containing only one IgG subclass protein in the second layer. The specificity of the third layer was assured by affinity purification of the rabbit anti-mouse IgG antibodies. The method was shown to be sensitive and specific. The test systems were timothy (Phleum pratense) pollen antigens and house dust mite (Dermatophagoides pteronyssinus) antigens.

Determination of IgE-containing immune complexes in human sera. Evaluation of polyethylene glycol precipitation of monomeric and complex IgE and of the detectability of IgE in the complexes

We studied the polyethylene (PEG) precipitability of monomeric human IgE, and of human IgE artificially complexed with rabbit anti-human IgE. At conditions where precipitation of monomeric IgE did not occur, from 0.2 to 20% of the complexed IgE was precipitated. The PEG precipitability of the complexes was inversely related to the IgE/anti-IgE ratio used for preparation of the complexes. From 1.5 to 19.2% of the IgE in the redissolved precipitates could be detected by use of a two-site IgE immunoradiometric assay, the percentage being highest for complexes formed at equivalence. We conclude that exact quantitation of circulating IgE immune complexes (IC) probably is impossible by any PEG precipitation assay. However, the optimized assay was found to be useful for identification of IgE IC in sera with total IgE concentrations below 5,000 U/ml. IgE IC were found in 5/20 sera from patients with Felty's syndrome, in 5/39 sera from patients with extrinsic allergy and high levels of specific IgE, and in 1/17 sera from immunized wasp allergics. No IgE IC were found in 20 normal human sera.

A modified crossed radioimmunoelectrophoretic method for determination of allergen-specific IgG antibodies. Elimination of non-specific binding by use of F(ab')2-fragments of rabbit antibodies and 125I-labelled protein A

A crossed radioimmunoelectrophoretic (CRIE) method for detection of specific IgG antibodies in patients' sera against horse hair and dander was developed. The unacceptably high non-specific binding encountered when substituting 125I-labelled antihuman IgG for 125I-labelled antihuman IgE in an ordinary CRIE was eliminated by the combined use of 125I-labelled Protein A as detector, and F(ab')2-fragments of the allergen-specific rabbit antibodies. The low background binding thus obtained makes the method useful for detection of specific IgG in sera where the ratio between specific and non-specific IgG is low. Therefore the method should also be applicable to other antigen/allergen systems.