Human serum amyloid A has cytokine-like properties

Scand J Immunol. 1998 Oct;48(4):410-8. doi: 10.1046/j.1365-3083.1998.00394.x.


Human serum amyloid A (SAA) proteins are a group of 12-14 kDa apolipoproteins found predominantly in the high-density lipoprotein (HDL) fraction of plasma. Several functions have been proposed for SAA, but its primary physiological function remains elusive. In this report, we used the monocytic cell line THP-1 to investigate whether recombinant SAA1 (rSAA) or the HDL-rSAA protein complex can affect the capacity of these cells to produce inflammatory cytokines in vitro. Incubation of rSAA, plasma HDL (which contains < or = 30 microg/ml of SAA) or HDL-rSAA complex with THP-1 cells induced synthesis of IL-1beta, IL-1ra and sTNFR-II protein and mRNA. The induction of cytokine synthesis was not due to endotoxin contamination since the effect was abrogated by protein denaturation. The rSAA and HDL-rSAA complex did not induce detectable levels of IL-6 or TNFalpha protein or mRNA. In contrast 10 microg/ml LPS stimulated secretion of the inflammatory cytokines, IL-1beta, IL-6 and TNFalpha, as well as IL-1ra and sTNFR-II from THP-1 cells. We confirmed that rSAA has chemoattractant properties in vivo, by subcutaneous injections into mice and examined the histology of the injection site at 72 h, however, the HDL-rSAA complex has a substantially reduced effect.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cells, Cultured
  • Cytokines / biosynthesis*
  • Cytokines / drug effects
  • Humans
  • Lipoproteins, HDL / metabolism
  • Lipoproteins, HDL / pharmacology
  • Mice
  • Monocytes / drug effects
  • Monocytes / metabolism*
  • Polymerase Chain Reaction
  • RNA, Messenger / biosynthesis
  • Recombinant Proteins / metabolism
  • Recombinant Proteins / pharmacology
  • Serum Amyloid A Protein / metabolism*
  • Serum Amyloid A Protein / pharmacology*


  • Cytokines
  • Lipoproteins, HDL
  • RNA, Messenger
  • Recombinant Proteins
  • Serum Amyloid A Protein