A procedure for the measurement of hormone receptors using a cell harvesting machine

A procedure has been developed that will rapidly measure the binding of hormones and growth factors to suspensions of intact cells. Radiolabeled ligand is bound to cells in 96-well cluster plates, and the cells are then collected and washed on glass fiber filters using a cell harvester. Up to twelve wells can be processed simultaneously in less than a minute. This rapid washing and harvesting method is convenient to use with a large number of samples, and the amount of bound ligand is saturable and proportional to cell number. This procedure should be applicable to suspension cultures, loosely adhering monolayer cultures, and other cellular preparations that will bind to porous filters. Using this procedure, we have shown that HeLa S3 cells grown in suspension cultures saturably bind to epidermal growth factor (EGF). The quantity of EGF bound to HeLa S3 cells can be increased by adding glucocorticoids to the culture medium.