Serum concentrations of allergen-specific IgG antibodies in inhalant allergy: effect of specific immunotherapy.

The occurrence of antibodies belonging to IgG class of immunoglobulins with specificity for short ragweed and Bermuda grass in the sera of nonatopic subjects and patients with inhalant allergy (at the time of initial diagnosis, following specific immunotherapy was investigated with an enzyme immunoassay. The intra-assay and inter-assay coefficients of variation for this assay ranged from 1.74%-4.62% and 3.18%-9.12%, respectively. IgG antibodies were found in the sera of the majority of nonatopic and all of atopic subjects. The differences in the concentration of these antibodies between these three groups were statistically significant (P less than 0.001). Specific immunotherapy resulted in a rise in the serum levels of allergen-specific IgG antibodies and, following an initial period of modest increase, a decrease in the level of allergen-specific IgE antibodies. Specific IgG response correlated with both the cumulative antigen dose and the clinical benefit that accrued from specific immunotherapy (P less than 0.001). The increase in the serum concentration of specific IgG was most pronounced in patients with high RAST scores at the time of initial diagnosis (P less than 0.001). The concentrations of short-ragweed specific IgG antibodies assayed with multiple samples in three patients with ragweed hay fever appeared not to be affected by the short-ragweed season to any significant degree. We conclude that direct enzyme immunoassay for allergen-specific IgE and IgG antibodies are useful in vitro monitors of immunologic responses to specific immunotherapy for inhalant allergy.

Immunochemical LD1 assay for myocardial infarction.

The diagnostic efficiency of an immunochemical assay for LD1 (I-LD1) was compared with an electrophoretic procedure for this isoenzyme (E-LD1) in 100 consecutive patients hospitalized for a clinical suspicion of acute myocardial infarction (MI). All patients were investigated with a standard protocol including serial determinations of total creatine kinase (CK) and lactic dehydrogenase (LD) activities, CK and LD isoenzymes, and electrocardiograms. Thirty-two patients were diagnosed to have acute MI on the bases of positive CK-MB or EKG or both. The coefficients of variation for the intraassay and interassay precision of I-LD1 assay ranged from 3.12% to 7.69%. Direct correlation between the I-LD1 and E-LD1 was very satisfactory (r = .961; P = less than .001). When the results of these two procedures were compared in terms of decision values for acute MI, there was agreement between them in 87 patients. At the cut-off point of 90 U/L, I-LD1 assay was 100% sensitive and 89% specific for acute MI; the corresponding figures for E-LD1 were 81% and 91%, respectively. The diagnostic efficiencies of the I-LD1 and E-LD1 procedures were 93% and 88%, respectively. A substantial saving in technologist time with the I-LD1 assay over the E-LD1 procedure was documented in this study.

Localization of IgE in tissues by an immunoperoxidase technique.

An indirect immunoperoxidase technique was used to study the content and distribution of IgE in formaldehyde solution-fixed, paraffin-embedded adenoid and nasal tissues of atopic and nonatopic persons. Adenoid tissue from 15 patients, and nasal tissue from five patients with symptoms of inhalant allergies and augmented serum levels of total and allergen-specific IgE were examined with this method. Adenoid tissues from five patients without allergic symptoms were studied for comparison. A rich content of IgE, largely within the cytoplasm of the plasma cells, was observed in tissues of atopic subjects. The sections from nonallergic persons contained few weakly staining IgE-positive cells. These observations provide anatomic support for the role of IgE in hypersensitivity reaction of immediate type. This immunoperoxidase technique, circumventing the principal shortcomings of the immunofluorescence procedures, affords a highly sensitive and practical approach to cellular and tissue localization of IgE.

A comparative study of the diagnostic characteristics of the modified RAST and Pharmacia CAP System.

New in vitro technology for the detection of allergen-specific IgE antibody continues to be developed. The manufacturer of one such system, the Pharmacia CAP System, claims that it has test qualities similar to those of the modified RAST. To evaluate this assertion we compared the results obtained with 12 allergens by both procedures on six negative control sera and four sera obtained from atopic patients; a total of 120 tests were performed. The data suggest that attempts to match the sensitivity of the modified RAST are accompanied by a significant loss in test specificity in the Pharmacia CAP System.

PRIST, RAST, and beyond. Diagnosis and therapy.

The measurement of total and specific IgE antibody by in vitro methods offers a significant advance in the diagnosis and management of allergic patients. These tests allow the physician to combine a precise diagnosis with an evaluation of patient sensitivity to provide care in a cost-effective manner.

In vitro testing methodologies. Evolution and current status.

Almost 25 years after the development of the radioallergosorbent test, in vitro technology has become firmly established as an outstanding diagnostic tool for physicians treating the allergic patient. The American Academy of Otolaryngic Allergy (AAO), in its most current position statement, endorses the modified RAST as reproducible, sensitive, and specific. A new organization called the American In Vitro Allergy and Immunology Society (AIVAIS) has been formed to promote and monitor the use of these tests. Both societies suggest that in vitro tests should be part of a complete clinical evaluation by a well informed physician knowledgeable about the contraindications and limitations of in vitro technology. Such physicians should be capable of incorporating this information into responsible, judicious, and effective management of allergic patients. Only after the correct diagnosis has been made can appropriate treatment be started. Whichever route you choose, you and your patients can benefit from the use of in vitro allergy testing.

A study of optimum dose immunotherapy in pharmacological treatment failures.

Forty-six patients with allergic rhinitis who were refractory to antihistamine/decongestant drugs were entered into a study to evaluate the effectiveness of optimal dose immunotherapy. Of the patients described, 91% reported symptomatic improvement within 24 weeks. Total IgE was seen to decrease in 76% of the patients in the same time frame. Nasal eosinophilia and specific IgE antibodies also were seen to decrease substantially. The results of this study indicate that immunotherapy, based on the patient's sensitivity as measured by specific serum antibody titers and titrated skin end points, is effective in alleviating symptoms and altering abnormal immunological factors.

Localization of IgE in adenoids and tonsils: an immunoperoxidase study.

An immunoperoxidase technique was applied to the localization of IgE in formaldehyde-solution-fixed, paraffin-embedded tissue. The content and distribution of IgE in tonsil and adenoid tissues from ten patients with histories of inhalant allergies and elevated serum levels of total and allergen-specific IgE were investigated. Compared with tissues from five nonatopic subjects, the tissues from atopic individuals were observed to harbor a much larger population of IgE-formating plasma cells. The profusion of IgE plasma cells in nasopharyngeal lymphoid tissue, observed in this study, furnishes strong anatomic evidence for a pathogenetic role of IgE in inhalant allergies. For cellular and tissue localization of IgE, the immunoperoxidase technique offers clear advantages over previously used immunoflorescence procedures.

An immunoperoxidase method for the demonstration of allergen-specific IgE in serum.

A solid-phase immunoenzymatic technique for the detection of allergen-specific IgE antibodies in serum is described. The binding of such antibodies to allergen insolubilized on cyanogen bromide-activated paper discs was detected by a subsequent two-step procedure involving the use of rabbit antihuman IgE and goat antirabbit IgG coupled with peroxidase. A solution of 3-3' diaminobenzidine and hydrogen peroxide, employed as the color indicator system, turned the discs dark brown in positive cases. Discs carrying 11 different inhalant allergens were tested with sera containing allergen-specific IgE antibodies. Agreement between the results of this technique and the RAST was seen in 85% of 310 tests performed. In the clinical practice of otorhinolaryngologic allergy, this test may prove to be an important laboratory adjunct ot clinical history and diagnostic skin test in the identification of the incriminated inhalant allergens.

Correlation of the diagnostic skin test with the immunoperoxidase assay in ragweed hypersensitivity.

The results of the diagnostic skin test are correlated with those obtained with an immunoperoxidase (IP) assay in 17 patients with positive histories for ragweed hay fever. The IP assay, a version of the ELISA technique, employs polystyrene microtiter plates as the solid-phase, horseradish peroxidase as the enzymatic label and O-phenylene diamine as the enzyme substrate. Concordance between the results of these two diagnostic techniques was observed in 66 patients (86%). Among the 11 patients with discordant results the modified RAST test was in agreement with the IP assay in seven and with the diagnostic skin test in four patients. In these latter four patients ragweed-specific IgE antibodies were detected by the IP or the modified RAST assays in low titers. The coefficients of variation for the IP assay ranged from 8% to 14.3%. The pros and cons of the use in vitro tests (the IP and the RAST test) and the diagnostic skin test in clinical practice of allergy are discussed.

Assay of IgE antibodies against June and Timothy grasses by an immunoperoxidase technique.

The results of eighty assays for serum IgE antibodies against June and Timothy grass antigens with a solid-phase immunoperoxidase technique are correlated with those obtained with the RAST procedure. The allergens were insolubilized in polystyrene microtitre plates. After allowing the allergen-specific IgE antibodies in the test serum to bind the allergen, the plates were incubated with horseradish peroxidase-conjugated rabbit antihuman IgE. The enzyme bound to the plates was assayed spectrophotometrically using o-phenylene diamine as the substrate. The coefficients of variation for within-batch reproducibility ranged from 4.57 to 11.97%, and those for between-batch variance from 8.25 to 13.7%. The slope of absorbance values of the immunoperoxidase assay is shallower than that of the bound radioactivity in the RAST technique. Notwithstanding, the immunoperoxidase method allows separation of non-atopic controls from the sera containing specific IgE antibodies and categorization of positive sera into weakly, moderatley, and strongly positive results. Free of the disadvantages inherent in the use of radioactive material, this assay offers an alternative to the RAST test for the assay of allergen-specific IgE antibodies.

An immunoperoxidase assay for serum ragweed-specific IgE.

A solid-phase enzyme immunoassay for allergen-specific IgE antibodies in serum is descirbed. In this technique these antibodies are allowed to bind to the allergen previously adsorbed to the wells of polystyrene microtiter plates. After a washing step the tubes are incubated with rabbit antihuman IgE labelled with horseradish peroxidase. Following a second washing step, the enzyme bound to the tubes is assayed spectrophotometrically using O-phenylene diamine as the substrate. The standard curves obtained with this method and with the RAST technique are illustrated. For the assay of serum antiragweed IgE antibodies, concordance between the results obtained with the RAST test and this immunoperoxidase assay was observed in 85 or 95 (90%) patients with symptoms of ragweed hayfever. The coefficients of variation ranged from 4.4% (2SD +/- .010) TO 14% (2SD +/- .008). The advantages of using peroxidase as the enzymatic marker for the assay of allergen-specific IgE are discussed.