Identification of a membrane glycoprotein associated with haemopoietic progenitor cells

A monoclonal antibody (3C5) is described which selectively binds to progenitor cell populations in human bone marrow and foetal liver. Mature, lymphoid (T,B) colony forming cells do not express the antigen. The antibody identifies a cell surface glycoprotein of mol. wt approximately 100,000 which might have an important regulatory role in early haemopoietic differentiation.