eBook: Multiplex Technology Guide - 19

Figure 4. Heatmap visualization of relative analyte concentrations measured by the Luminex (LMX) and Meso Scale Discovery (MSD)
multiplex assays. Cytokine measurements were performed in plasma samples from healthy individuals and from people with diabetes
or elevated procalcitonin (PCT) levels. A histogram showing the color key used to designate sample concentrations is provided at the top
left of the main image. Each cell represents a single analyte in a single plasma sample. Black cells indicate cytokine levels in that sample
that were measured to be the approximate mean of all evaluated samples. Red cells indicate higher (above average) measured cytokine
values for that sample/assay combination and green cells indicate lower (below average) analyte concentrations, with color intensity
indicating magnitude of difference. Grey cells mean that sample data for that specific analyte were not available. Samples that provided
signals below the lower limit of quantification (LLoQ) for any analyte had those values artificially entered as their specific LLoQ value
before calculation and mapping.

However, cytokines typically function in complex interactive networks.23,24 Multiplex immunoassay technologies have advantages over singleplex ELISAs, notably simultaneous quantification of many bioactive
molecules within a small sample volume to quickly
generate distinct patient-specific expression profiles
of plasma cytokines.4 This is particularly important
with rare or limited-volume samples such as pediatric blood draws and cerebrospinal fluid specimens.

for the MSD assays. Three MSD 96-well assays (maximum 10-plex) were needed to sufficiently overlap
with most of the 21 cytokines evaluated on a single
LMX plate.

Discussion
Quantification of individual circulating cytokines
by ELISA is an essential research and clinical tool.22

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