Neutrophil association and degradation of normal and acute-phase high-density lipoprotein 3

E. G. Shephard, F. C. De Beer, M. C. De Beer, M. S. Jeenah, G. A. Coetzee, D. R. Van Der Westhuyzen

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33 Scopus citations


The interaction of normal and acute-phase high-density lipoproteins of the subclass 3 (N-HDL3 and AP-HDL3) with human neutrophils and the accompanying degradation of HDL3 apolipoproteins have been studied in vitro. The chemical composition of normal and acute-phase HDL3 was similar except that serum amyloid A protein (apo-SAA) was a major apolipoprotein in AP-HDL3 (approx. 30% of total apolipoproteins). 125I-labelled AP-HDL3 was degraded 5-10 times faster than 125I-labelled N-HDL3 during incubation with neutrophils or neutrophil-conditioned medium. Apo-SAA, like apolipoprotein A-II (apo-A-II), was more susceptible than apolipoprotein A-I (apo-A-I) to the action of proteases released from the cells. The amounts of cell-associated AP-HDL3 apolipoproteins at saturation were up to 2.8 times greater than N-HDL3 apolipoproteins; while apo-A-I was the major cell-associated apolipoprotein when N-HDL3 was bound, apo-SAA constituted 80% of the apolipoproteins bound in the case of AP-HDL3. The associated intact apo-SAA was mostly surface-bound as it was accessible to the action of exogenous trypsin. α1-Antitrypsin-resistant (α1-AT-resistant) cellular degradation of AP-HDL3 apolipoproteins also occurred; experiments in which pulse-chase labelling was performed or lysosomotropic agents were used indicated that significant intracellular degradation occurred which points to the involvement of cell-surface proteases in this degradation.

Original languageEnglish
Pages (from-to)919-926
Number of pages8
JournalBiochemical Journal
Issue number3
StatePublished - 1987

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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