Simple purification method of the antiphospholipid antibody from normal human plasma

We have reported that rabbit serum contains a phospholipid (PL)/ganglioside-binding protein which adsorbs to Sephacryl S-400 gel and agglutinates human red blood cells. A new protein similar to the PL/ganglioside-binding protein was simply purified from normal human plasma using Sephacryl S-400, Sepharose CL-4B and DEAE-Sepharose CL-6B columns. The purified protein was found to agglutinate rabbit red blood cells. The hemagglutination was specifically inhibited by two PL, phosphatidylserine and phosphatidylinositol, but not by any other PL, gangliosides, saccharides or glycoproteins tested. From analyses of the N-terminal amino acid sequence and immunological specificity, the protein was identified to be a human immunoglobulin M.