Repetitive A epitope (type 3 chain A) defined by blood group A1-specific monoclonal antibody TH-1: chemical basis of qualitative A1 and A2 distinction

Proc Natl Acad Sci U S A. 1985 Feb;82(4):1199-203. doi: 10.1073/pnas.82.4.1199.

Abstract

The IgG2a monoclonal antibody TH-1, which reacts specifically with blood group A1 but with neither A2 nor O erythrocytes, has been established. The antibody reacted only with A1 erythrocytes in hemagglutination and antibody absorption assays; it did not react with A2 erythrocytes, even after trypsin or sialidase treatment. This antibody detected, on TLC immunostaining, a series of glycolipids from A1 erythrocytes but virtually none or very weak bands from A2 erythrocytes. It did not react with type 1 or type 2 chain A, or with globo-A. The simplest reactive component was isolated from a previously assigned Ab fraction by HPTLC of acetylated compounds. The structure of the reactive component was characterized by 1H NMR spectroscopy, methylation analysis, and enzymatic degradation, as shown below: (Formula: see text). The structure is essentially a repetitive A epitope attached to type 2 chain and is hereby called type 3 chain A. The determinant can be carried on extended and/or branched structures, but it was not detectable in glycoproteins. The structure was characteristic of A1 erythrocytes and present in only trace amounts in A2 erythrocytes. The precursor H (Fuc alpha 1----2Gal beta 1----3GalNAc alpha 1----3[Fuc alpha 1----2]Gal beta 1----4GlcNAc beta 1----R; type 3 chain H) was present in greater quantity in A2 erythrocytes than in A1 erythrocytes, but it was absent in both O and B erythrocytes. The A1 transferase apparently can transfer alpha-GalNAc to type 3 chain H, while the A2 transferase may not have this ability.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • ABO Blood-Group System / immunology*
  • Antibodies, Monoclonal / immunology
  • Antibody Specificity
  • Antigen-Antibody Reactions
  • Carbohydrate Sequence
  • Epitopes / immunology
  • Glycolipids / immunology
  • Glycoproteins / immunology
  • Humans

Substances

  • ABO Blood-Group System
  • Antibodies, Monoclonal
  • Epitopes
  • Glycolipids
  • Glycoproteins