Monoclonal

The immune system normally produces a mixture of antibodies against a target (polyclonal); the 1975 hybridoma technique of Köhler and Milstein made it possible to immortalise a single antibody-producing cell and harvest one uniform antibody from it. Early monoclonals were mouse proteins that the human body rejected; successive generations were chimeric (-ximab), humanised (-zumab) and fully human (-umab), and are now produced in cultured mammalian cells at ton scale. The word also describes tumours themselves: cancers are clonal, descending from a single cell, though they diversify into subclones over time.