2 Introduction
Measuring the antibody response to multiple antigens in biofluids can be achieved using the xMAP® technology supplied by Luminex®. For the multiplexing assay all antigens are covalently bound to small paramagnetic particles (MagPlex™) of unique fluorescence dye combination making it possible to distinguish between the mixed spheres in the full assay.
The immune response to some antigens can be extremely strong and extremely weak to others. Thus, the quantitative dynamic range of analysis extends over several orders of magnitude. In a standard measurement, the patient’s plasma/serum is diluted 1000-fold and / or 10000-fold. Since this commonly used approach carries the risk of generating quantitative data close to the detection limit when including multiple antigens with a wide variance in the expected antibody responses. This results in error prone data sets making the interpretation of the data very difficult. An advanced approach has been developed to overcome this issue including a serial dilution based measurement of samples granting results derived from the linear range of each antigen.
Figure 2.1: serological assay workflow using the xMAP® technology
The resulting complex data set could not be analyzed to date. Therefore, an iterative analysis procedure was developed and implemented using the programming language R and the shiny framework resulting the the xMAPr app.