The history of monoclonal antibody development – Progress, remaining challenges and future innovations

Liu, Justin K.H.

Monoclonal antibodies are monovalent antibodies which bind to the same epitope and are produced from a single B-lymphocyte clone [4] . They were first generated in mice in 1975 using a hybridoma technique [5] . The generation of hybridomas involves immunising a certain species against a specific epitope on an antigen and obtaining the B-lymphocytes from the spleen of the animal. The B-lymphocytes are then fused (by chemical-or virusinduced methods) with an immortal myeloma cell line lacking the hypoxanthine-guanine-phosphoribosyltransferase (HGPRT) gene and not containing any other immunoglobulin-producing cells. These hybridoma cells are then cultured in vitro in selective medium (i.e. medium containing hypoxanthine-aminopterinthymidine) where only the hybridomas (i.e. the fusion between the primary B-lymphocytes and myeloma cells) survive as they have inherited immortality from the myeloma cells and selectiveresistance from the primary B-lymphocytes (as the myeloma cells lack HGPRT, they cannot synthesise nucleotides de novo as this is inhibited by aminopterin in the selective medium) [4] . The initial culture of hybridomas contains a mixture of antibodies derived from many different primary B-lymphocyte clones, each secreting its own individual specific antibody into the culture medium (i.e. the antibodies are still polyclonal). Each individual clone can be separated by dilution into different culture wells. The cell culture medium can then be screened from many hundreds of different wells for the specific antibody activity required and the desired Blymphocytes grown from the positive wells and then recloned and retested for activity [6] . The positive hybridomas and monoclonal antibodies generated can then be stored away in liquid nitrogen.