Platelet-activating factor biosynthesis induced by various stimuli in human HaCaT keratinocytes

J Invest Dermatol. 1996 Jul;107(1):88-94. doi: 10.1111/1523-1747.ep12298295.


Platelet-activating factor (PAF) is a potent inflammatory mediator that is thought to play a role in cutaneous inflammation. These studies used mass spectrometry to examine the molecular species of PAF precursor glycerophosphocholine lipids (GPC) as well as the biosynthesis of PAF and other sn-2 acetyl-GPC in a human keratinocyte-derived cell line (HaCaT keratinocytes). Approximately 28% of HaCaT keratinocyte GPC consisted of 1-alkyl species, and the relative amounts of the sn-1 alkyl constituents of the PAF precursor 1-alkyl-2-acyl-GPC were as follows: hexadecyl > octadecenyl > octadecyl. Ionophore (A23187)-stimulated HaCaT keratinocytes synthesized both PAF (1-hexadecyl, 1-octadecenyl, and 1-octadecyl species) and less potent 1-acyl analogs (1-palmitoyl, 1-oleoyl, and 1-stearoyl species). PAF production was rapid and maximal by 10 min. The major species of sn-2acetyl-GPC at 2.5 min were 1-hexadecyl-2-acetyl-GPC (2.2 ng/10(6) cells) and 1-palmitoyl-2-acetyl-GPC (2.4 ng/10(6) cells). HaCaT keratinocytes also synthesized PAF and 1-acyl PAF analogs when stimulated with the peptide growth factor endothelin-1 and the nonhydrolyzable PAF receptor agonist carbamyl-PAF. Both 1-hexadecyl-2- acetyl-GPC and 1-palmitoyl-2-acetyl-GPC stimulated intracellular calcium mobilization in HaCaT cells, indicating that these sn-2 acetyl-GPC act in autocrine fashion. These studies revealed that the human keratinocyte-derived cell line HaCaT can synthesize significant amounts of PAF and 1-acyl analogs in vitro from both nonspecific (A23187) and specific (endothelin-1, carbamyl-PAF) stimulation, suggesting a role for this inflammatory lipid mediator in keratinocyte pathophysiology.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Calcimycin / pharmacology
  • Calcium / metabolism
  • Cell Line
  • Endothelin-1 / pharmacology
  • Humans
  • Intracellular Membranes / metabolism
  • Keratinocytes / metabolism*
  • Platelet Activating Factor / analogs & derivatives
  • Platelet Activating Factor / biosynthesis*
  • Platelet Activating Factor / pharmacology
  • Stimulation, Chemical


  • Endothelin-1
  • Platelet Activating Factor
  • Calcimycin
  • 1-O-hexadecyl-2-N-methylcarbamol -sn-glycerol-3-phosphocholine
  • Calcium