TAL-1 PROTEIN EXPRESSION IN VASCULAR-LESIONS

The distribution of TAL-1 protein, an important vascular promoter in m ice, has been examined immunohistochemically in a range of human vascu lar lesions and normal tissues. Formalin-fixed, paraffin-embedded vasc ular lesions including granulation tissue, haemangiomas, Kaposi's sarc omas, spindle cell haemangioendotheliomas, and angiosarcomas, were exa mined using a monoclonal antibody to recombinant TAL-1. Endothelial ce lls in all lesions gave positive immunostaining of variable intensity. Granulation tissue and spindle cell areas of the vascular tumours gav e the strongest staining (nuclear and cytoplasmic). The better-differe ntiate endothelial cells within the tumours and resident well-formed v essels were less positive and some cells were in fact negative. The ma lignant endothelial cells in angiosarcomas showed less intense positiv e staining than KS cells. This study has shown TAL-1 protein expressio n in a range of reactive, benign, and malignant vascular lesions. Prot ein expression appears to be stronger in the spindle cell areas, perha ps reflecting greater expression in less-differentiated endothelial ce lls. (C) 1997 by John Wiley & Sons, Ltd.