Accuracy of IgE antibody laboratory results.
BACKGROUND
Studies have demonstrated that the magnitude of sensitization as evidenced by specific IgE (sIgE) levels provides significant information as to whether a sensitized individual is likely to be truly reactive. However, it is not clear that quantitative sIgE results provided by different laboratories using different technologies are comparable.


OBJECTIVE
To investigate whether similar results were obtained from Clinical Laboratory Improvement Act-certified laboratories that used 3 common systems for sIgE antibody determination with serum samples and mouse-human IgE chimeric antibodies with known specificity and quantity.


METHODS
Sixty samples for peanut and 20 for soy were submitted for sIgE determination on 3 different systems: ImmunoCAP, Immulite, and Turbo radioallergosorbent test (RAST). Mouse-human chimeric IgE antibodies specific for the major birch allergen Bet v 1 and for the dust mite allergen Der p 2 were also included.


RESULTS
A qualitative evaluation using a cutoff of 0.35 kUA/L showed some differences in the ability to detect sIgE sensitization, with the Turbo RAST being most variable. However, considerable differences were found with quantitative evaluation, with Immulite overestimating and Turbo RAST underestimating sIgE compared with ImmunoCAP. Similar discrepancies were seen with the mouse-human chimeric IgE antibody samples.


CONCLUSIONS
These findings have potentially serious clinical implications, since each of these systems is widely used. It is therefore important that all laboratories clarify which system they are using. Just because 2 systems present their results in the same units does not mean that the results are necessarily correct or interchangeable.
Wood
Robert A
RA
Pediatric Allergy and Immunology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287, USA. rwood@jhmi.edu
Segall
Nathan
N
Ahlstedt
Staffan
S
Williams
P Brock
PB
D000485:Allergens / Q000276:immunology; D000818:Animals; D039741:Antigens, Dermatophagoides / Q000276:immunology; D052179:Antigens, Plant; D010367:Arachis / Q000276:immunology; D060829:Arthropod Proteins; D005512:Food Hypersensitivity / Q000175:diagnosis / Q000276:immunology; D006801:Humans; D006967:Hypersensitivity / Q000175:diagnosis* / Q000276:immunology; D007073:Immunoglobulin E / Q000032:analysis / Q000276:immunology*; D051379:Mice; D011993:Recombinant Fusion Proteins / Q000276:immunology; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012698:Serologic Tests / Q000379:methods / Q000592:standards / Q000706:statistics & numerical data; D013025:Glycine max / Q000276:immunology
D000485:Allergens; D039741:Antigens, Dermatophagoides; D052179:Antigens, Plant; D060829:Arthropod Proteins; C451163:Dermatophagoides pteronyssinus antigen p 2; D011993:Recombinant Fusion Proteins; D007073:Immunoglobulin E