Flowmetrix multiplex sandwich immunoassays using fluorescent microbeads as solid support.
Experiences with the LabMAP (Luminex)
system
Dept. of Clinical Biochemistry,
Statens Serum Institut,
The
LabMAP technology is based on flowmetric analysis of different coloured fluorescent microbeads that act as solid basis for the assay reactions.
Different reactions, using the same fluorophore as
reporter, takes place simultaneously on different beads that subsequently are
identified and quantitatively read by the Luminex 100
instrument. We have focused on multiplex sandwich immunoassays, employing different
monoclonal capture antibodies coupled to different beads, biotinylated
detection antibodies and streptavidin labelled phycoerythrin as a sensitive common reporter. The
distinction between assays for the different analytes
is thus based on the fluorescent characteristic of the different beads. The luminex 100 can differentiate between 100 differently
coloured beads and therefore in theory it is possible to run 100 different
assays simultaneously. We have developed multiplexed immunoassays to measure
cytokines in different medias including serum, bloodspots
and cell culture supernatants. In house panels containing assays for more than
20 different analytes with sensitivities around 10 pg/ml have been developed, but smaller panels are
in most cases recommended. Experiences, strengths, shortcomings and problems
will be discussed.