Rosemay Vazeux

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

Cellualar adhesion molecules are newly identified mediators of angiogenesis. Infantile hemangiomas, characterized in the early stages by a proliferation of poorly differentiated vessels followed in the late stages by a vascular differentiation and regression of the tumor, represent an interesting model to study angiogenesis. We studied by immunohistochemistry the distribution of HLA‐DR and three adhesion molecules ICAM‐3. E‐selectin and VCAM‐I on endothelial cells in different stages of vessel differentiation in infantile hemangiomas. We found high levels of ICAM‐3 expression on proliferating vessels, while its expression was low or undetectable on well differentiated vessels. A different set of E‐selection antibodies showed a more heterogenous pattern of distribution and VCAM‐1 antigens were found in both proliferating and differentiated vessels. HLA‐DR expression on endothelial cells was inversely correlated to the vascular differentiation. Our results are consistent with the hypothesis that ICAM‐3 plays a role in the early stages of vessel formation. Our results also suggest that variation of E‐selectin and HLA‐DR expression may be related either to vessel differentiation or may reflect the acquisition of an activated endothelial cell status.