To maintain consistency of protocol and chemistry of assay components among assays for detection of allergen specific IgE, the IgG ELISA procedures used throughout this study mimics that of the previously characterized IgE macELISA for both dogs and cats. The results presented herein characterize a single ELISA that is designed to detect specific IgG to different environmental and food antigens in the sera of both dogs and cats that might provide a foundation for determining the validity of such testing. Consequently, the clinical utility of these serum tests for detection of antigen specific IgG remains unclear. Unfortunately, very few studies have been published that characterize the assays used for these evaluations. A multitude of commercially available services are offered that range from monitoring allergen specific IgG following immunotherapy to those assays which purportedly define antigens that are involved with food hypersensitivity and/or intolerance.
In concert with these assays for detection of allergen specific IgE, ELISAs for detection antigen specific IgG have also been introduced and substantial claims for the utility of these assays have been set forth in various promotional materials.
The utility of these IgE specific assays in confirming allergy diagnosis and providing a basis for selection of allergens to be included in immunotherapeutic regimes has been reasonably well established. Some of the commercially available assays have been well characterized and their functionality are continually monitored. In recent years, information has been presented to document the advancements made in enzyme linked immunosorbent assays (ELISA) for detection of allergen specific IgE in companion animals. clinical sensitivity and specificity) for various antigens, especially those contained in food stuffs.ĭog IgG, Cat IgG, ELISA, Environmental Antigens, Food Antigens Collectively, the results provide a foundation for future studies intended to address the issues associated with the validity of IgG testing (i.e. The results demonstrate the reproducibility and robustness of the assay and define its utility in detecting IgG specific for a number of different environmental and food antigens. Approximately 30% of the sample responses were within the lower range of detection (0 – 1000 EAU) and approximately 50% of all responses were in the mid-range (1001 – 3000 EAU) of detection, while the remaining 20% of sample response were in the upper range of detection (3001 – 4000 EAU) or beyond the limits of the assay.
Evaluation of multiple samples from both cats and dogs, at a dilution of 1: 3000, against a panel of 24 environmental antigens (59 individual samples) and 24 food antigens (54 individual samples) demonstrate that IgG reactivity to all of these antigens is present in the majority of samples. The intra-laboratory % CV among reactive calibrators remained relatively constant at 11.8% (range 7.4% – 13.1%), while the background variance was calculated to be only slightly higher at 14.0%. The average inter-assay variance for each of the operators was indistinguishable the average % CV was calculated to be 10.6% (range 7.0% – 14.6 %). No substantial difference in responses between operators were noted the average intra-assay % CV for positive calibrators was calculated to be 5.7% (range 1.3% – 12.9%) and 8.3% (range 3.2% – 19.2%) for background responses. An admixture of these anti-IgG-biotin antibodies (25nG/mL each) was optimized to yield similar responses with reactive calibrators for the two species. The reactivity of multiple lots of affinity purified anti-IgG specific to the fc component of dog IgG or cat IgG, and subsequently biotinylated, were evaluated against varying dilutions of both cat and dog sera. The purpose of this study was to develop and characterize an enzyme linked immunosorbent assay for detection of antigen specific IgG in dogs and cats that might be used to document the clinical validity of IgG testing in these animals.
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