Regional differences in constitutive and induced ICAM-1 expression in vivo

Am J Physiol. 1995 Dec;269(6 Pt 2):H1955-64. doi: 10.1152/ajpheart.1995.269.6.H1955.


The aim of the present study was to characterize and compare the expression of intercellular adhesion molecule 1 (ICAM-1) on unstimulated and endotoxin-challenged endothelial cells in different tissues of the rat. ICAM-1 expression was measured using 125I-labeled anti-rat ICAM-1 monoclonal antibody (MAb) and an isotype-matched control MAb labeled with 131I (to correct for nonspecific accumulation of the binding MAb). Under baseline conditions, ICAM-1 MAb binding was observed in all organs. The binding of 125I-ICAM-1 MAb varied widely among organs, with the largest accumulation (per g tissue) in the lung, followed by heart (1/30th of lung activity), splanchnic organs (1/50th of lung activity), thymus (1/100th of lung activity), testes (1/300th of lung activity), and skeletal muscle (1/800th of lung activity). Endotoxin induced an increase in ICAM-1 MAb binding in all organs except the spleen. Endotoxin-induced upregulation of ICAM-1 was greatest in heart and skeletal muscle (5- to 10-fold), whereas the remaining organs exhibited a two- to fourfold increase in ICAM-1 expression. Maximal upregulation of ICAM-1 occurred at 9-12 h after endotoxin administration. A dose-dependent increase in ICAM-1 expression was elicited by 0.1-10 microgram/kg, with higher doses (up to 5 mg/kg) producing no further increment. Induction of ICAM-1 mRNA after endotoxin was observed in all tissues examined (lung, heart, intestine), peaked at 3 h, and then rapidly returned to control levels. These findings indicate that ICAM-1 is constitutively expressed on vascular endothelium in all organs of the rat and that there are significant regional differences in the magnitude and time course of endotoxin-induced ICAM-1 expression.

Publication types

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

MeSH terms

  • Animals
  • Antibodies, Monoclonal
  • Cells, Cultured
  • Endothelium, Vascular / cytology
  • Endothelium, Vascular / metabolism
  • Endotoxins / pharmacology
  • Intercellular Adhesion Molecule-1 / genetics
  • Intercellular Adhesion Molecule-1 / metabolism*
  • Iodine Radioisotopes
  • Male
  • RNA, Messenger / metabolism
  • Rats
  • Rats, Sprague-Dawley
  • Tissue Distribution


  • Antibodies, Monoclonal
  • Endotoxins
  • Iodine Radioisotopes
  • RNA, Messenger
  • Intercellular Adhesion Molecule-1