Early expression of intercellular adhesion molecule-1 in the corneal endothelium stimulated by endotoxin: an immuno-scanning electron microscopical study.

Three-dimensional localization of the intercellular adhesion molecule-1 (ICAM-1) in the corneal endothelium stimulated by Salmonella typhimurium endotoxin was investigated using immuno-scanning electron microscopy (SEM). Samonella typhimurium endotoxin, 100 micrograms, was injected in Lewis rats weighing 200 grams. The animals, including the controls, were sacrificed and both eyes enucleated at 0, 3, 12 and 24 hours after injection (n = 3 each time). After resection, the corneas were immersed in hypothermic University of Wisconsin solution with monoclonal mouse-anti-rat ICAM-1 IgG and then goat-anti-mouse IgG coupled to 15 nm gold particles. Then the corneas were prepared conventionally for scanning electron microscopy. Histotopographical examination with immuno-SEM revealed that ICAM-1 antigen increased on the corneal endothelium by 3 hours postinjection. The particles were arranged along the cytoplasmic processes, especially at the summits. The number of particles was 3.3 +/- 0.8/microns2 in the control, 3.6 +/- 0.8/microns2 at 0 hour, 14.4 +/- 0.9/microns2 at 3 hours, 25.4 +/- 1.4/microns2 at 12 hours, and 22.7 +/- 2.6/microns2 at 24 hours postinjection. ANOVA indicated that the time-course was an important factor (P < 0.01). Our results showed that ICAM-1 could be augmented in the corneal endothelium by endotoxin. The interrelationship between ICAM-1 expression and cytoplasmic processes seems to be important for the neutrophil-binding mechanism.