An immunoassay technique that is bead-based and allows quantitation of multiple analytes like metabolic markers, cytokines, chemokines, etc in a single biological matrix sample is Luminex Multiplex Assay. The multiplex immunoassay can be used for detecting and quantitating biomarkers in the given samples for evaluation of the safety and efficacy of the drug/therapeutics. The technique is also used in bioanalytical studies utilizing biomarkers and cell-based assays for kidney, cardiac, inflammation, cancer, intracellular cell signaling, toxicity, apoptosis, and obesity.
The high-performance multiplex assay kits are considered a valuable asset for basic and translational research of diseases where simultaneous analysis of multiple proteins is involved, like interferons, members of tumor necrosis family, chemokines, interleukins, etc.
The results from the Luminex assay are considered equivalent or superior to a conventional ELISA assay. Using commercial or custom kits one can detect up to 100 compatible analytes with the help of a Luminex protein assay. This is one of the major reasons why Luminex cytokine assays have emerged as one of the most demanded biomarker testing services.
The basic procedure for Luminex Multiplex Assay is:
- In a sample containing various target proteins and Luminex beads pre-coated with specific capture abs, the Luminex beads are incubated.
- These beads are then washed off and incubated again with detection antibodies that are target-specific biotinylated. This results in sandwiching the target proteins between the capture and detection antibodies.
- Further again, the beads are washed off and incubated with PE (phycoerythrin)-streptavidin-PE(conjugated streptavidin).
A chain consisting of bead-target protein-capture Ab (fluorescent)-biotinylated target-specific Ab—streptavidin-PE is formed if your sample contains the target of any given biotinylated antibody.
Helping in recognizing and quantifying targets in the sample while a high-speed digital signal processor manages the fluorescent output can be done with the help of this Luminex Multiplex assay.
Coronavirus or the SARS-CoV-2 is the pathogenic cause of COVID-19 disease in humans. The viral RNA for this pathogen is encapsulated with nucleocapsid protein which in turn is enveloped in M/membrane protein. The spike proteins surrounding the inner core have subunits S1 and S2 as well as RBC (receptor binding domain) that binds with human cellular ACE2 receptors. Post binding with the receptor, the virus takes over the cellular machinery. These structural proteins of the virus induce an immune response to infection. The first response is produced with the help of IgM, followed by IgG and IgA. Testing the serum or human plasma for these Igs binding to Coronavirus antigen can help in the identification and quantitation of the viral infection.
As mentioned previously, Luminex cytokine assay allows the identification of multiple proteins in the sample. It also provides a highly sensitive and specific result by targeting three different antigens using an algorithm to determine infection positivity.
The xMAP technology (the world’s most used multiplexing technology) helps in building several new multiples serological tests for the detection of antibodies released on exposure to different SARS-CoV-2 antigens. This is another added benefit of the Luminex protein assay to test coronavirus inflation and cytokine storm.