Bioscience Reports 3, 577-588 (1983) 577 Printed in Great Britain A multiplicity of erythrocyte glycolipids of the neolacto series revealed by immuno-thin-layer chromatography with monoclonal anti-I and anti-i antibodies K. UEMURA% R. A. CHILDS*, P. HANFLAND**, and Ten FEIZI* * Applied Immunochemistry Research Group, Clfnical Research Centre, Watford Road, Harrow, Middlesex HA1 3UJ, U.K.; and ** Institute for Experimental Haematology and Blood Transfusion, University of Bonn, D-3500 West Germany (Received 13 June 1983) The thin-layer-chromatography immunostaining procedure was applied to human erythrocyte glycolipids using monoclonal anti-i and anti-I antibodies which are directed against epitopes on linear and branched carbohydrate chains of the neolacto (poly-N-acetyl- lactosamine) series. An examination of native and mild-acid-treated glycolipids from normal adult (Iadul t antigen type), neonatal (icord) , and I-antigen-deficient adult (iadul t) erythrocytes enabled certain structural inferences to be made as follows: (a) cells of both I and i phenotypes contain a multiplicity of glycolipids of the neolacto series whose backbones consist of $ or more sugar residues; (b) the octasaccharide backbones are predominantly linear in cells of i phenotype and branched in those of I type; and (c) more complex glycolipids having decasaccharide and larger backbones with both linear and branched sequences occur in erythrocytes of both phenotypes, 0 The natural-monoclonal autoantibodies of man with anti-I and anti-i specificities are among the most extensively studied monoclonal antibodies against carbohydrate structures which behave as differ- entiation antigens (I~2). Two hybridoma antibodies with anti-I specificities have also been described recently (3). The antigens recognized by anti-I and -i antibodies are developmentally regulated on human erythrocytes (I,~) such that the i antigen, associated with linear oligosaccharides of the neolacto series, is the predominant antigen expressed on human foetal erythrocytes while I antigen, associated with branched oligosaccharides~ predominates on erythrocytes of adults. Rarely this maturation process does not occur and a high level of i antigen persists in adulthood. Inhibition-of-binding studies using structurally defined oligosaccharides and glycolipids have shown (9,3) that individual anti-I antibodies recognize different carbohydrate domains on the branched ceramide octasaccharide structure 01983 The Biochemical Society