Expression of adhesion molecules on the endothelium of normal tissue vessels and vascular tumors

Endothelial cells are important in initiating adhesive processes between circulating cells and extracellular structures and changes in their distribution are believed to be important in many pathologic conditions. Since little is known about the detailed distribution of adhesion molecules in human endothelium in different sites and circumstances, the present study has undertaken a detailed analysis of 5 of the putative most important adhesion molecules on a wide range of normal tissue endothelium. We have compared this reactivity with that seen in a comprehensive range of vascular tumors both benign and malignant.

Fresh samples of a wide range of normal tissues and vascular tumors were stained by antibodies against the following adhesion molecules; intercellular adhesion molecule-1 (CD54), E-selectin (endothelial cell adhesion molecule-1), vascular cell adhesion molecule-MUC-1, P-selectin (platelet activation-dependent granule to external membrane protein, CD62) and MUC-18 using either the APAAP immuno-alkaline phosphatase or an immunoperoxidase method.

Labeling of the endothelial cells in different normal tissues with intercellular adhesion molecule-1, P-selectin, and MUC-18 was heterogeneous both in terms of vessel size and strength of staining. Vascular cell adhesion molecule-1 and E-selectin were largely absent. The vascular tumors were likewise variable in their staining patterns which frequently differed from the immunophenotype of the reactive vessels surrounding the tumor.

This study demonstrates that the expression of adhesion molecules of the immunoglobulin and selectin family on normal tissue endothelium, and vascular tumors is much less predictable than that obtained with other vascular markers such as F8 RA, CD31, CD34, and CD36. Adhesion molecules show considerable heterogeneity of expression on vascular endothelium which presumably reflects their varied functions on different types of vessel. In general their expression is markedly reduced on vascular tumors.