The use and limitation of monoclonal antibodies against mononuclear phagocytes.

Monoclonal antibodies have been used to study receptors on the plasma membrane of macrophages, as well as the processes of membrane synthesis, internalization, recycling and macrophage differentiation and activation. Various immunisation and screening procedures have been employed. Most reagents produced so far are not restricted to macrophages in their binding specificity. Monoclonal antibodies have been of great use in characterising murine Fc receptors and in studying the composition of the membrane of pinocytic vesicles. Antibody F4/80 has been used to examine the behaviour of the 160K membrane protein it defines during macrophage differentiation and activation. This antigen is absent on macrophage precursors, is expressed in relatively large amounts on mature macrophages, but expression is diminished on activated populations. No macrophage subset heterogeneity has been defined by ag F4/80 or 2 other monoclonal antibody-defined macrophage antigens, as all bone marrow-derived macrophage clones express these antigens. Anti-macrophage antibodies have already proved useful as diagnostic markers and in cell separation. Reagents such as these will help to sort out relationships between macrophages and other presumptive mononuclear phagocytes.