Partial characterization of circulating macromolecular beta 2-microglobulin complexes by density gradient...

beta 2-microglobulin (beta 2m)-containing, rapidly sedimenting peaks were seen when sera of patients with 3% polyethylene glycol (PEG)-insoluble beta 2m were fractionated by sucrose density gradient ultracentrifugation. No such material was found in serum of a healthy volunteer without 3% PEG-insoluble beta 2m. MW of beta 2m-containing high molecular weight fractions ranged from 1.6 X 10(5) to 2.1 X 10(6). When some fractions were recentrifuged a majority of beta 2m was recovered at the original sedimentation position. Analysis of high molecular weight beta 2m-containing peaks by SDS-PAGE followed by electroblotting revealed only monomeric beta 2m indicating that beta 2m was not covalently bound in the high molecular weight material.