Thursday, May 2, 2013

Applications Thursday: The RAST assay performed by the PHERAstar FS on CSI

Last nights episode of CSI: Las Vegas employed the PHERAstar FS to aid in the determination of a victims allergy to latex. This was accomplished using a RAST assay. RAST stands for radioallergosorbent test and uses radioactivity. This has been replaced by a similar test that does not use radioactivity; the fluorenzyme immunoassay or FEIA. In the episode at approximately 19:00 they run what appears to be a colorimetric assay that looks at a panel of potential allergens.

 Degranulation processes 1 - antigen; 2 - IgE antibody;
3 - FcεRI receptor; 4 - preformed mediators
(histamine, proteases, chemokines, heparine);
5 - granules; 6 - mast cell;7 - newly formed mediators
(prostaglandins, leukotrienes, thromboxanes, PAF)
FEIA measures allergen-specific IgE bound to standardized allergens. Results are reported semiquantitatively, with values correlating with the probability of clinical reactivity. Compared with another common allergy test, the skin prick test, FEIA is slightly less sensitive but may have a greater positive predictive value.

Since this procedure typically uses a solid phase to which antigens are bound; several washing and incubation steps are necessary before the final fluorescent signal can be detected. So, in addition to not being colorimetric, the type of mix and read assay depicted in the episode is not entirely accurate. However,this is an application that could certainly employ a PHERAstar FS to perform the final analysis!

We thank CSI: Las Vegas for considering our reader for use on their show. We at BMG LABTECH were happy to help!