ICAM-3 and E-selectin endothelial cell expression differentiate two phasesof angiogenesis in infantile hemangiomas

Cellular adhesion molecules are newly identified mediators of angiogenesis. Infantile hemangiomas, characterized in the early stages by a proliferatio n of poorly differentiated vessels followed in the late stages by a vascula r differentiation and regression of the tumor, represent an interesting mod el to study angiogenesis. We studied by immunohistochemisty the distributio n of HLA-DR and three adhesion molecules ICAM-3, E-selectin and VCAM-1 on e ndothelial cells in different stages of vessel differentiation in infantile hemangiomas. We found high levels of ICAM-3 expression on proliferating ve ssels, while its expression was low or undetectable on well differentiated vessels. A different set of E-selectin antibodies showed a more heterogenou s pattern of distribution and VCAM-1 antigens were found in both proliferat ing and differentiated vessels. HLA-DR expression on endothelial cells was inversely correlated to the vascular differentiation. Our results are consi stent with the hypothesis that ICAM-3 plays a role in the early stages of v essel formation. Our results also suggest that variation of E-selectin and HLA-DR expression may be related either to vessel differentiation or may re flect the acquisition of an activated endothelial cell status.