A comparability study of the emerging protein array platforms with established ELISA procedures. 
Recent developments in microarray technology have made it possible to perform immunoassays in a multiplexed format.  This ability is highly desirable given the potential for greater throughput analysis.  In spite of the obvious advantages, a number of issues arise as a result of multiplexing the reactions.  In this study, we have assessed the performance characteristics that are associated with the transfer of technology from a uniplexed to a multiplexed format.  Two solution phase array platforms were chosen for this study: the commercially available Luminex(100) xMap system (Austin, Texas, USA) and the UltraPlex technology devised by SmartBead Technologies Ltd. (Cambridge, UK).  For this comparative study, a test for the presence of six autoantibodies in a selection of human patient serum samples was chosen as a model system.  The multiplexed Luminex xMap and SmartBead UltraPlex assays were generally comparable.  However, both systems generated some results that were at variance with those obtained by ELISA.  The different methods used for the assignment of the cut-off levels for each of the assays within any given platform was identified as the major source of these non-concordant results.  The present study demonstrates that array platforms have the potential to be used in immunodiagnostics providing that suitable cut-off levels are established.