Integrin modulating factor-1: a lipid that alters the function of leukocyte integrins

Cell. 1992 Jan 24;68(2):341-52. doi: 10.1016/0092-8674(92)90475-r.


The avidity of integrin CR3 (also known as alpha M beta 2, Mac-1, Mo-1, and CD11b/CD18) may be reversibly altered without changes in the number of cell surface receptors. Here we describe a molecule termed integrin modulating factor (IMF-1), which controls CR3 avidity. Addition of IMF-1 to polymorphonuclear leukocytes (PMNs) or to purified CR3 causes enhanced binding of ligand. IMF-1 is not present in resting PMNs, but stimulation of cells results in a transient rise in IMF-1 content that parallels a transient rise in CR3 activity. We suggest that PMNs control adhesivity by controlling synthesis of IMF-1, which then acts as an allosteric activator of leukocyte integrins. IMF-1 is an acidic, amphiphilic molecule of Mr340 +/- 16 that does not contain ester, phosphate, amide, sialic acid, or glycosidic or vicinal hydroxyl functionalities, but does contain a carbon-carbon double bond. These results suggest that IMF-1 is an unsaturated fatty acid or an isoprenoid acid.

Publication types

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

MeSH terms

  • Cell Adhesion / drug effects
  • Cell Adhesion / physiology*
  • Fatty Acids / chemistry
  • Fatty Acids / physiology*
  • Fatty Acids, Unsaturated / chemistry
  • Fatty Acids, Unsaturated / physiology*
  • Flow Cytometry
  • Kinetics
  • Macrophage-1 Antigen / chemistry
  • Macrophage-1 Antigen / drug effects
  • Macrophage-1 Antigen / metabolism
  • Macrophage-1 Antigen / physiology*
  • Neutrophils / drug effects
  • Neutrophils / metabolism
  • Neutrophils / physiology*
  • Tetradecanoylphorbol Acetate / pharmacology


  • Fatty Acids
  • Fatty Acids, Unsaturated
  • Macrophage-1 Antigen
  • integrin modulating factor 1
  • Tetradecanoylphorbol Acetate