Lipid coating of paramagnetic microspheres reduces non-specific binding to Kelly neuroblastoma cells

In an effort to reduce non-specific binding interactions (binding in the absence of antibody), sheep anti-mouse IgG1 (Fc) antibody linked to magnetic microspheres (also referred to as microbeads or beads) were treated with phosphatidylcholine (PC), phosphatidylglycerol (PG), or a mixture of PC and PG. The lipid-treated microspheres were mixed with Kelly neuroblastoma cells, which had been pre-labelled with Hoechst fluorochrome. After 30 minutes of incubation, the microsphere adherent cells were separated from the non-adherent cells and counted. PC or mixed lipid treatment of beads reduced nonspecific binding to 8.3%, compared to 25.8% in the untreated samples. PG, on the other hand, increased non-specific binding. Lipid treatment of beads did not adversely affect specific antibody mediated binding. When a non-specific antibody was added to the incubation mixture, non-specific binding of untreated control beads to cells was increased, but binding of PC-treated beads was unaffected.