Simultaneous analysis of eight human Th1/Th2 cytokines using microarrays.

The adaptive immune system induces T cells to change from a naive phenotype to a Th1/Th2 phenotype each of which produce characteristic types of cytokines. Knowledge of whether a specific immune response is Th1 or Th2 is a useful indicator for diseases with basis in immune function disorder. An assay that can rapidly analyze multiple cytokines indicative of these two cell types from small sample quantities can be an extremely useful research and diagnostic tool. Silanized glass slides were printed with multiple arrays of capture antibodies to detect eight different cytokines involved in the Th1/Th2 response along with control proteins for assessing assay performance. Arrays were developed by sequential addition of known antigen amounts, detector antibodies and a fluorescent detection system followed by imaging and quantification. These arrays were used to determine the specificity, sensitivity and reproducibility of the assay and the performance compared with conventional ELISA. This multiplexed assay is able to measure human Th1/Th2 cytokines in sample volumes lower than 20 microl. The assay sensitivity for the eight cytokines range from 0.3 microg/l for IL-4 to 6.4 microg/l for IL-5 which are either comparable to or higher than those reported for conventional ELISA or bead-based multiplex ELISA methods. This assay can be automated to measure expression levels of multiple Th1/Th2 cytokines simultaneously from tens to hundreds of biological samples. This assay platform is more sensitive and has a larger dynamic range as compared to a conventional ELISA in addition to significantly reducing the time and cost of assay. This platform provides a versatile system to rapidly quantify a wide variety of proteins in a multiplex format.