EAA™ (Endotoxin Activity Assay) FAQ
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Q. How does the EAA™ detect endotoxin?
A. The EAA™ detects endotoxin by employing a highly specific IgM antibody with a strong affinity to the Lipid-A portion of endotoxin (Lipopolysaccharide, LPS)
Q. What is the difference between EAA™ and the LAL assay?
A. The EAA™ is a semi quantitative test for endotoxin activity in whole blood. The LAL is a quantitative test for endotoxin in colloidal solutions. The LAL cannot reliably and reproducibly detect endotoxin in whole blood, plasma, or serum.
Q. What is the sensitivity of the EAA™?
A. The analytical sensitivity for the EAA™ was estimated from the precision observed in a low EAA™ level sample. The sensitivity was calculated based on extrapolation of the observed standard deviation in the low level sample to a “zero” EAA™ level. The overall EAA™ mean was 0.106 with a standard deviation of 0.021 EA units. The analytical sensitivity can be estimated by applying the standard deviation to a hypothetical measurement of “zero” EA units where the analytical sensitivity is equal to 2 times the SD or 0.042 EA units.
Q. What is the specificity of the EAA™?
A. The EAA™ is specific to Gram-Negative Lipopolysaccharide (Endotoxin). The EAA™ does not detect gram positive bacterial, or yeast cell wall components as no reactivity is observed when lipoteichoic acid extracts up to 2000 pg/mL are tested for the following strains of Gram positive bacteria: S. mutans, S. pyogenes, S. sanguis, S. faecalis, S. aureus and B. subtilis. Similarly, there was no reactivity of yeast mannan up to 2000 pg/mL and cell wall extracts of C. albicans and A. fumagatis.
Q. Where does specificity of the EAA™ for LPS come from?
A. The specificity of the EAA™ is due to the highly specific IgM antibody used for the detection of endotoxin.
Q. What is the range of the EAA™?
A. The EAA™ will provide an endotoxin activity result normally between 0.0 and 1.0. The EA result correlates with a low (0.0-0.39), intermediate (0.4-0.59) or high (≥0.60) endotoxin activity level.
Q. What is the LLD/LOD of the EAA™?
A. The analytical sensitivity of the EAA™ is 0.042 EA units. This is approximately 20-50 pg/ml of endotoxin, depending on bacterial species of origin and neutrophil response.
Q. What is the molecular form of the endotoxin that the assay detects?
A. The EAA™ detects antibody-complexed endotoxin in the disaggregated form.
Q. In which animal species is the EAA™ known to work, in which species is it known not to work?
A. The intended use of the EAA™ is to measure endotoxin activity in Human whole blood. However, there are publications available demonstrating the assay’s utility in measuring endotoxin activity in Horses and Dogs. There are ongoing unpublished studies utilizing the EAA™ in measuring endotoxin activity in Pigs. The EAA™ cannot be used to determine the Endotoxin Activity in Mice as the antibody contained in the assay is Murine IgM.
Q. What specimens can be used with EAA™?
A. The sample specimen must be whole blood drawn via indwelling catheter or venipuncture. The sample can be stored at room temperature (18-25OC) in an EDTA anticoagulated draw tube, and must be used to run the EAA™ within 3 hours of draw.
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