[3H]AA incorporation in T cells. Splenic T cells were cultured for 48 hr with (open circles) or without (closed circles) anti-CD3 mAb, then incubated with [3H] AA (1 μCi/ml) for up to 60 min. At varying times, cells were harvested and labeled AA incorporation was quantified. Inset, Tritiated thymidine incorporation, assessed daily for 3 days, in T cells cultured with (open circles) or without (closed circles) anti-CD3 mAb. The results are the mean and standard error of 3 separate experiments.