Evaluation of Gene Expression Profiling by QuantiGene™ 2.0 RNA Assay.

QuantiGene™ 2.0 technique could be used to investigate the gene expression signature of the immune system senescence and thus to understand the molecular mechanism involved in the defects of the immune response during aging.QuantiGene™ 2.0 technique is a multiplex platform allowing the simultaneous analysis of several target RNA molecules (up to 80) present in a single sample. QuantiGene Assays use an accurate method for multiplexed or for single gene expression quantitation. QuantiGene 2.0 uses magnetic beads which are dyed internally with two fluorescence dyes, exhibiting a unique spectral signal and providing specificity and multiplexing capability of the technique. QuantiGene Assays incorporate branched-DNA technology for gene expression profiling.Branched-DNA system is responsible for the high sensitivity of the system. In fact, it permits to detect low levels of mRNA molecules. This branched-DNA system allows for the direct measurement of RNA transcripts by using signal amplification rather than target amplification. The assay protocol is spread over 2 days. First, immune cells are lysed to release the target RNA, which is incubated with oligonucleotide probe set targeted with beads capable to hybridize with the target RNA. Signal amplification is performed by sequential hybridization of the branched-DNA pre-amplifier, amplifier, and label probe molecules. The last step involves the incubation with Streptavidin-conjugated R-phycoerythrin. The fluorescent reporter generates a signal directly proportional to the levels of RNA molecules present in the cells. Luminex instrument evaluates the median intensity of fluorescence, which is proportional to the number of RNA target molecules present in the cells.