Use of iron- or selenium-coupled monoclonal antibodies to cell-surface antigens as a positive selection system for cells.

A system which confers selective growth advantage to cells expressing particular surface proteins would be extremely desirable, for such a technique would allow the study of receptors using somatic cell genetic techniques such as DNA-mediated cell transformation and selection of over-producing cell variants. Polypeptides bound to surface receptor, and antibodies bound to surface antigens generally are taken up efficiently by cells by endocytotic mechanisms. Several investigators have accordingly developed useful techniques for selection against cells expressing surface receptors and antigens, using hormones and antibodies conjugated to toxins. We reasoned that conjugation of nutrients to antibodies or hormones conversely might permit a positive selective pressure to be applied in appropriately constituted medium. We report here that monoclonal antibodies to cell-surface antigens will indeed deliver nutritional iron and selenium to cultured cells in an antigen-specific manner.