Immunoassay By: Kimberly Martin, Asia Pupa, Adrian Hernandez, & Omar Roldan

What is it? o Chemical test that detects the presence or quantity of a drug in blood or urine o relies on specific antigen-antibody reactions o can be qualitative or quantitative o It is made by injecting the drug and a protein into an animal o This acts as an antigen which stimulates the animal to make antibodies o The serum is removed from the animal as it contains antibodies specific to the drug. The serum is added to blood/urine samples in a testing laboratory. o 3 commonly used: radioimmunoassay, enzyme multiplied immunoassay, & flourescence polarization immunoassay

AssayStrengthsWeaknesses Enzyme-linked immunosorbent assay (ELISA) Widely-used, high- throughput, inexpensive Requires temperature control, more qualitative than quantitative, time- and-labor intensive Western blot Highly sensitive and specific Complicated laboratory diagnostic Immunofluorescent antibody assay (IFA) Relatively simple to perform Less sensitive than ELISA, requires microscopy to evaluate Electrochemoluminescen ce Sensitivity More applicable to commercial laboratory setting Magnetic immunoassaysQuantitative Requires a magnetic reader that may limit its field application

How is it used? o Many clinical tests are immunoassays o Many home pregnancy tests o detect the hormone chorionic gonadotropin o Tests to assess heart disease measure enzyme CK- MB o Measures insulin to assess hypoglycemia (low blood sugar) o Detects prostate cancer by measuring prostate- specific antigens o Used in anti-doping labs to test athletes for recombinant human growth hormone

How is it used? Cont’d o It is most commonly used as the drug test for marijuana o Also commonly used to measure other drugs, hormones, proteins, tumor markers, and signs of cardiac injury, and diseases like malaria and Robles disease (river blindness)

StrengthsWeaknesses o widely used o inexpensive o quick o easily automated o high sensitivity o false-positive results o medications can crossreact with the test o hard to determine all possible substances that can cause a false-positive o different people can show different results o does not tell when drug was taken o needs to be followed by confirmatory testing

Case Example An unidentified man died in a horrible work accident. It was suspected that the man had misused drugs because he was acting strangely. The man had climbed to the top floor of the building and had reportedly screamed out that he was "superman" and plummeted to a grisly death. After the body was recovered (in terrible condition), a sample of the man's blood was taken and an immunoassay test was performed. His blood was tested for the common hallucinogens: LSD, Mescaline, and PCP. A color change occurred when the PCP antibody was added. Therefore, it was concluded that the deceased man had taken PCP before his death. © Joanna

Works Cited Saferstein, Richard. "Forensic serology."Forensic science: an introduction. Upper Saddle River, N.J.: Pearson/Prentice Hall, Print. "Immunoassay." Encyclopedia of Drugs, Alcohol, and Addictive Behavior. Ed. Rosalyn Carson-DeWitt. Vol. 2. Gale Cengage, 2001.eNotes.com. 2 Apr, "Immunoassays." BIO Ventures for Global Health. N.p., n.d. Web. 2 Apr < Primer/Targets/cid/ViewDetails/ItemID/13.

1.Which Immunoassay Technique is the most common? a. Enzyme-Linked Immunosorbent Assay ( ELISA ) b. Western Blot c. Electrochemoluminescence 2.Name one advantage of using an immunoassay. 3.What is an example of a test where an immunoassay is helpful 4.What drug is the most commonly detected by an immunoassay test? 5.Why is the immunoassay test used in sports anti-doping laboratories?