Gregory L. Jacob

Measurement of the absolute levels of IgE antibodies in patients with ragweed hay fever: Effect of immunotherapy on seasonal changes and relationship to IgG antibodies☆

Abstract The effect of immunotherapy with aqueous ragweed pollen extract on changes in IgE antibody was analyzed in 40 untreated patients with ragweed hay fever and compared to changes in 63 treated patients. Treated patients received cumulative doses prior to and during treatment ranging from 1.4 × 10 5 to 4.8 × 10 6 protein nitrogen units (PNU). IgG antibody to ragweed antigen E (AgE) was measured by radioimmunoprecipitation, while IgE antibody to allergens in crude ragweed extract was measured by the radioallergosorbent test (RAST). The RAST procedure was calibrated using a serum whose content of IgE antibody in nanograms per milliliter had been determined by immunoabsorption, and with this method the absolute quantities of IgE antibodies to ragweed allergens could be measured. Control experiments indicated that the IgG antibodies in the sera of the treated patients did not interfere with the measurements of IgE antibodies. The levels of IgE antibody in serum varied from less than 5 ng/ml to approximately 3,000 ng/ml. IgE antibodies decreased from October, 1973, to July, 1974, and rose sharply from July to October, 1974, following the pollination season. In both untreated and treated patient groups the magnitudes of the decreases were related (p

Immunoglobulin E antibodies to pollen allergens account for high percentages of total immunoglobulin E protein

The quantities of immunoglobulin E (IgE) antibodies to grass or ragweed allergens were measured by an immunoabsorption in the serums of patients sensitive to one of these allergens. IgE antibodies to grass or ragweed allergens accounted for means of 30 and 29 percent of the total IgE protein. After the ragweed pollination season, the levels of serum IgE antibodies to ragweed allergens rose dramatically and in postpollination serums they accounted for 39 percent of the total IgE protein with a range from 13 to 50 percent.

Serum IgG4 concentrations and allergen-specific IgG4 antibodies compared in adults and children with asthma and nonallergic subjects

We describe the development of specific immunoassays for IgG4 protein and for allergen-specific IgG4 antibodies. We also measured the concentrations of IgG4 protein and determined the frequencies of detectable IgG4 antibodies to several common allergens in sera from adults and children with asthma and from nonallergic subjects. Serum concentrations of IgG4 protein increase with age but are not different in children with asthma and nonallergic children, nor does a raised serum concentration predict a severe clinical course in childhood asthma. IgG4 antibodies to milk and egg are common in children and adults and are more common in children with asthma than in nonallergic children less than 3 years of age. The presence of detectable IgG4 antibodies or a raised concentration of IgG4 protein in serum is not useful empirically as a diagnostic indicator of asthma but more likely results from antigen exposure occurring at mucosal surfaces.

Agreement of anti-neutrophil cytoplasmic antibody measurements obtained from serum and plasma.

Serum and plasma are used interchangeably to measure anti‐neutrophil cytoplasmic antibodies (ANCA), even though the release of ANCA target antigens during the preparation of serum could affect ANCA assays and cause discrepancies between the results obtained from serum and plasma. To what extent ANCA test results obtained from serum agree and correlate with results from plasma remains unknown. Therefore, a comprehensive comparison was performed using serum and plasma samples which were collected in 175 patients with active Wegeners granulomatosis at enrolment of a recent randomized trial. These paired serum and plasma samples were subjected to parallel ANCA testing by standard indirect immunofluoresence on ethanol‐fixed neutrophils, a direct enzyme‐linked immunoassay (ELISA) for proteinase 3 (PR3)‐ANCA and myeloperoxidase (MPO)‐ANCA, and two different capture ELISAs for PR3‐ANCA. The concordance of categorical serum and plasma ANCA results was assessed using κ‐coefficients. These were > 0·8 for all assays, indicating a very good concordance between positive and negative serum and plasma results. Spearmans correlation coefficients for serum and plasma PR3‐ANCA values obtained by direct ELISA and both capture ELISAs were ≥ 0·95 (P < 0·0001). Our study shows that serum and plasma samples can be used interchangeably for measuring ANCA.

Analytic accuracy of specific immunoglobulin E antibody results determined by a blind proficiency survey

Analytic variability affects the accuracy of measurements of specific IgE antibodies, but the frequency of false results attributable to analytic variability is not well documented. We have monitored the accuracy of the results generated in our laboratory by testing aliquots of positive serum pools and a negative serum pool submitted blindly for the measurement of IgE antibodies to 16 different allergens, including foods; weed, grass, and tree pollens; mites, molds, and epithelia; and Hymenoptera venoms. Positive serum pools were prepared to contain modest amounts of IgE antibodies. Tests were performed by immunometric assays with microcrystalline cellulose allergen immunosorbents. Frank false-positive and false-negative results were very uncommon when binding levels were classified by a ratio-based reporting scheme. False-borderline results were more common. A borderline result is truly equivocal and may or may not indicate the presence of low levels of IgE antibodies. Analytic variability adds uncertainty to the measurement of small quantities of IgE antibodies regardless of the classification scheme used to report test results.