Figure 1.

Protection from apoptosis induced by dThd deprivation in asynchronously growing cultures of TS⁻ and Thy4 by a Fas-inhibiting antibody that binds to FasL. For clonogenic assays, cells were plated as described and treated with the NOK-1 mAb (100 ng/ml; ▪), a mouse IgG1 isotype-matched control mAb (100 ng/ml; ▴), or no antibody (•) at the time of plating. Following overnight attachment, cells were washed with 2 ml of Hanks’ balanced salt solution (37°C) and subsequently deprived of dThd by refeeding with dThd-free medium containing the respective antibodies. At various times for up to 6 days, cells were rescued with dThd (20 μM) added to individual wells, and clonogenic survival was determined after a further 11 days. Data represent the mean ± SD of triplicate determinations.