Incorporation and turnover of [3H] AA within membrane phospholipids of proliferating and resting CD4+ and CD8+ T cells. Splenic T cells were culture as above for 48 hr with (open symbols) or without (closed symbols) anti-CD3 mAb, then enriched for CD4+ T cells (dashed triangles) or CD8+ T cells (circles) by negative selection. Following labeling with [3H]AA (1 μCi/ml) for 20 min, the cells were then washed and cultured at 37°C for 60 min in BME with 1% BSA. At the initiation (zero time) and conclusion of culture (60 min), cells were harvested, membrane lipids were extracted and free AA and phosphoglycerides were resolved by TLC. The concentration of free [3H]AA and of [3H]AA within different phospholipid molecular species was measured by liquid scintillation counting. Data are the mean of 2 experiments.