Immunogenetics

, Volume 27, Issue 3, pp 203–210

Biochemical complexity of serum HLA class I molecules

  • Lia M. E. Dobbe
  • Nico J. Stam
  • Jacques J. Neefjes
  • Marius J. Giphart
Article

DOI: 10.1007/BF00346587

Cite this article as:
Dobbe, L.M.E., Stam, N.J., Neefjes, J.J. et al. Immunogenetics (1988) 27: 203. doi:10.1007/BF00346587

Abstract

Human serum was found to contain a variety of class I-like molecules by Western blotting with anti-class I heavy chain reagents: major bands usually are observed around Mr 44 000, 40 000, and 35 000–37 000. HLA-A24-positive individuals are distinguished by higher serum levels of Mr 44 000 and 40 000 class I-like molecules than those found in HLA-A24-negative individuals. The Mr 44 000 serum molecules are probably intact class I molecules that have been shed from the cell membrane, because they contain both a transmembrane segment (TM), as deduced from detergent-binding experiments, and a cytoplasmic tail (CT), as inferred from reactivity with an antipeptide serum specific for the cytoplasmic domain of class I antigens (RaCT). The Mr 35 000 and 37 000 molecules contain neither a TM nor a CT region and therefore are probably proteolytic breakdown products of cellular and/or serum Mr 44 000 molecules, although the existence of Q10-like molecules in man cannot be ruled out. The Mr 40 000 molecules do not contain a TM region. Mr 40 000 molecules reactive with the RaCT serum were found in the minority (2/13) of sera tested. We conclude that alternative splicing resulting in a precise excision of the TM exon plays a minor role in the generation of serum HLA class I antigens.

Abbreviations used in this paper

B2m

beta-2 microglobulin

BSA

bovine serum albumin

EBV-BLCL

Epstein-Barr virus-transformed B lymphoblastoid cell line

mAb

monoclonal antibody

SDS-PAGE

sodium dodecyl sulfate-polyacrylamide gel electrophoresis

TCA

trichloroacetic acid

Copyright information

© Springer-Verlag 1988

Authors and Affiliations

  • Lia M. E. Dobbe
    • 1
  • Nico J. Stam
    • 2
  • Jacques J. Neefjes
    • 2
  • Marius J. Giphart
    • 1
  1. 1.Department of Immunohaematology and BloodbankUniversity Hospital LeidenLeidenThe Netherlands
  2. 2.The Netherlands Cancer InstituteAmsterdamThe Netherlands