REGN-846

An antiserum to stearyl-isomaltoheptaose-containing liposomes, R-856, with a high proportion of IgM and IgG antibodies was separated into IgM and IgG fractions by column chromatog.The IgM and IgG antibody binding sites were studied by quant. precipitin, precipitin inhibition, and competitive binding assays.Both were similar to unfractionated antibodies with sites complementary to isomaltotetraose.Another antiserum, R-846, was separated into antibody fractions of restricted homogeneity by preparative isoelec. focusing and their combining sites were studied by competitive binding.Two groups of site sizes were found.One complementary to isomaltopentaose, was similar to the unfractionated antiserum whereas the other had smaller size sites complementary to isomaltotetraose.