Identification, by immunoblotting, of the structures carrying Lutheran and para-Lutheran blood group antigens

Immunoblotting was performed, after sodium dodecyl sulphate polyacrylamide gel electrophoresis of solubilised red cell membranes under non-reducing conditions, with human Lutheran antibodies, anti-Lua, -Lub, -Lu3, -Lu6 and -Lu8, and with human para-Lutheran antibodies, -Lu4, -Lu12 and -Lu17. On antigen-positive red cells all antibodies revealed two components of apparent molecular weight (Mr) 83,000 and 76,000. Anti-Lua and -Lub gave no bands with Lu(a-b+) or Lu(a+b-) cells, respectively. With the exception of anti-Lu17, which reacted normally, and anti-Lu3, which reacted weakly, none of the antibodies showed bands with membranes from Lu(a-b-) cells of the In(Lu) type. Treatment of the red cells with sialidase led to a small reduction in the apparent Mr of the Lutheran glycoproteins which, therefore, appear to contain sialic acid bearing O-linked oligosaccharides.