EXPRESSION OF INTERCELLULAR-ADHESION MOLECULE-3 (ICAM-3 CD50) IN MALIGNANT LYMPHOPROLIFERATIVE DISORDERS AND SOLID TUMORS/

ICAM-3/CD50 is a recently described LFA-1 counter receptor that seems to play an important role in the initiation of immune responses. In th is study we have examined the expression of ICAM-3/CD50 in a large ser ies of human neoplasms including 101 Non-Hodgkin's lymphomas (NHL), 26 Hodgkin's disease, and 38 solid tumors to define the distribution pat terns of this molecule in malignant neoplasms and their possible corre lation with clinical and pathological characteristics of the patients. In NHL, ICAM-3/CD50 was expressed in almost all the tumors with a ten dency to be lost in high grade lymphomas. Reed-Sternberg cells and the ir variants in Hodgkin's disease were always negative independently of the histological subtype of the disease. No expression was observed i n tumor epithelial cells of the 38 solid tumors examined. Strong endot helial cell staining was observed in 31% of the NHL and 31% of Hodgkin 's disease. ICAM-3 expression in these cases was restricted to small t umor vessels. ICAM-3 expression in endothelial cells of NHL was signif icantly more frequent in high grade (40%) than in low grade lymphomas (14%) (p=0.012). In addition, tumor vessels were also positive in 29% of solid tumors independently of the histological type. No correlation was observed between ICAM-3 expression in tumor or endothelial cells and other clinical and pathological characteristics of the patients. T hese findings indicate that ICAM-3 expression in human tumors is restr icted to hematological neoplasms with a tendency to be lost in high gr ade lymphomas and Hodgkin's disease. ICAM-3 is also expressed by endot helial cells from tumor-associated neovascularization in both lymphoid and solid tumors.