INTERPRETIVE CONSIDERATIONS OF SOLID-PHASE ASSAYS
Defining a positive result
The numeric output of Luminex single antigen beads is a trimmed the mean fluorescence intensity along with other factors in determining a positive result: laboratories validate their single antigen beads assays with known negative and positive sera, establish a working mean fluorescence intensity threshold for antibody detection, and correlate this threshold with positive flow-cytometry cross-matching results as an important laboratory-specific standardization process within a program. Mean fluorescence intensity thresholds may be modified on the basis of patient history, control values, different HLA loci, recipient HLA typing, and consideration of epitope/antigen groups. As such, a strict mean fluorescence intensity level above which clinically relevant antibodies are consistently identified is challenging to define.