EXPRESSION OF ADHESION MOLECULES IN ENDEMIC AND EPIDEMIC KAPOSIS-SARCOMA

Spindle cells and vascular endothelium in nodular lesions of AIDS asso ciated (epidemic) and endemic Kaposi's sarcoma showed similar immunohi stochemical patterns of expression for cell adhesion molecules and ext racellular matrix proteins. Spindle cells as well as endothelium also expressed both alpha 5 and alpha V integrin subunits and ICAM-1 sugges ting a possible role for inflammatory cytokines in spindle cell format ion. The spindle cell compartment was rich in collagen, laminin, fibro nectin and tenascin suggesting an important reactive component in the evolution of Kaposi's sarcoma, The lack of thrombospondin expression i n the spindle cells favours the contention that they could be transiti onal, proliferating cells of endothelial origin. Specific expression o f tat protein was not seen suggesting minimal if any HIV replication i n these lesions, Our findings Suggest similar histopathogenetic mechan isms for endemic and epidemic Kaposi's sarcoma. The clinically more ma lignant features of most AIDS related cases may reflect an important e ffect of systemic and focal cytokines in HIV patients and possibly oth er cofactor(s), i.e. tat protein in the induction and growth of the le sions.