The use of polyethylene glycol (PEG) to enhance the adsorption of autoantibodies.

The use of polyethylene glycol (PEG) to enhance the adsorption of warm autoantibodies on red blood cells (RBCs) was evaluated in our laboratory in an effort to reduce the time and cost associated with routine differential adsorptions. Sera from 19 patients with warm autoantibodies were tested. Fourteen of these sera contained alloantibodies or additional autoantibody specificities underlying the dominant autoantibody. The sera were differentially adsorbed using equal volumes of serum, reagent RBCs, and PEG for 15 minutes at 37 degrees C. The PEG/serum mixture was harvested and used for testing. Six drops of the PEG/serum mixture were tested against reagent RBCs for 15 minutes at 37 degrees C. An antiglobulin test was then performed using anti-IgG. The PEG adsorption technique took a total of 10 hours to completely eliminate autoantibody reactivity in all 19 samples. The reference method required a total of 59.5 hours to adsorb the autoantibodies in all 19 samples. Two weak alloantibody specificities (anti-K, anti-Jkb), known to be present in the serum, were not detected in the PEG tests. Four specificities were weaker with the PEG adsorbed serum. All other alloantibody specificities (13) were detected with equal or greater strength in the PEG adsorbed serum. The use of PEG to enhance the adsorption of autoantibodies should be considered as an option to reduce the time and cost of labor-intensive differential adsorptions. Laboratories should be cautioned that weak alloantibodies may not be detected using this method.