The production and assessment of monoclonal antibodies to cortisol

In an extensive series of experiments, Balb/C mice and Lou rats were immunised with 3-0-(carboxymethyl)oximinocortisol conjugated to bovine serum albumin. The spleen cells from selected animals were fused with cells from mouse or rat plasmacytoma lines. Out of many hundreds of hybridomas screened, more than seventy produced antibody that bound 125I-labeled cortisol. These cultures were investigated further for stability of antibody production, affinity for cortisol and cross-reactivity with other steroids. An unexpected but consistent finding was that immunised rats produced antibody which cross-reacted with 11-deoxycortisol to a level greater than 100% and this characteristic was reproduced by rat-rat hybridomas. Strategies designed to improve the chances of generating non-cross-reactive anti-cortisol monoclonal antibodies did not appear to be successful. Nevertheless, several monoclonals were identified with properties that suggest they may be useful for the development of sensitive and specific cortisol assays.