The production of monoclonal antibodies specifying tumour associated antigens is illustrated by studies with a spontaneously arising rat mammary carcinoma (Sp4). Fusion of spleen cells from tumour-immune rats with mouse myeloma (P3NS1) yielded hybridomas secreting antibody reacting with a tumour specific antigen. These approaches have subsequently been used to produce monoclonal antibodies reacting with human osteogenic sarcoma, although in this case the antigens detected are tumour associated rather than tumour-specific.
The diagnostic applications of these monoclonal antibodies have been explored particularly to evaluate whether radiolabelled preparations can be used for ‘imaging’ tumours. This approach has been validated with the human osteogenic sarcoma xenograft in tests showing that tumours can be detected by y-camera scanning following injection of 131I-labelled antibody when used in conjunction with blood pool labelling using 113MIn and a computerised subtraction technique.
Monoclonal antibodies also have considerable potential for targetting drugs. These approaches are illustrated by studies using anti-rat mammary carcinoma Sp4 monoclonal antibody linked to adriamycin for therapy of subcutaneous tumour. In addition to drug conjugates, monoclonal antibodies are being used for targeting immunomodulating agents. This is illustrated by another series of studies in which the anti-human osteogenic sarcoma monoclonal antibody has been conjugated to human lymphoblastoid cell interferon to produce a reagent for activating host natural killer cells.