Spherotech‐EDTA combined serum treatment reduces background more effectively as compared to One Lambda Adsorb Out™ and LIFECODES Serum Cleaner in Luminex‐based solid‐phase immunoassays for HLA antibody detection

Abstract

Spherotech (SPT) microparticles capture non‐specific binding materials present in test serum, and EDTA removes the so called” prozone effect”. This study presents a novel approach of combined SPT‐EDTA serum treatment prior to Luminex HLA antibody testing to remove high background, and prozone effect in a single step process, and compared the efficacy of SPT‐EDTA serum pre‐treatment with AdsorbOut (ADS) and Serum Cleaner (SC) to reduce background in solid phase immunoassays (SPI). A total of 21 serum samples with a history of elevated negative control (NC) values ≥500, and 20 samples with normal NC values were included to assess the potential adverse effects. A problem of high background was noted in 25% of our samples in SPI. We observed 80% effectiveness in reducing NC values <500 with SPT‐EDTA serum pre‐treatment compared to 72%, and 67% for ADS and SC‐treated sera, respectively. Interestingly, we found a strong correlation in antibody‐binding levels between SPT versus ADS; and ADS versus SC‐treated sera for both phenotype and single antigen bead assays (p < 0.001). No adverse effect was noted on NC, positive control (PC) values, PC/NC ratios in the upfront use of SPT‐EDTA as compared to EDTA alone. Our data revealed that combined SPT‐EDTA treated sera is more effective than ADS, and SC in reducing high background in SPI. Taken together, SPT‐EDTA serum treatment prior to Luminex HLA Ab testing is cost‐effective, our laboratory saves nearly 30% of the annual total cost for Ab testing and improved test turnaround time by two business days.