Characteristics of the cell surface antigen, p72, associated with a variety of human tumours and mitogen-stimulated T-lymphoblasts.

The monoclonal antibody 791T /36, prepared against a human osteogenic sarcoma cell line, 791T , reacts with a variety of human tumours and also mitogen-stimulated PBMN cells. The target antigen as expressed upon 791T cells is a monomeric plasma membrane-associated glycoprotein with an apparent Mr of 72000. By quantitative flow cytofluorimetry, approx. 10(5) antibody molecules bound per cell to T-lymphoblasts induced with PHA or Con A, whereas only a few thousand antibody molecules bound per cell to unstimulated cells, so that the antigen may be classified as a lymphocyte activation antigen. On lymphoblasts, the 791T /36 again reacted with a protein with an apparent Mr of 72000. This antigen therefore has a dual role as a tumour marker and lymphocyte activation antigen which may be implicated in the regulation of cell proliferation.