CD8A and neoplasm: Early studies indicated that coculture of activated T‐cells with tumor cells, their supernatants or serum samples from cancer patients, but not with normal fibroblasts or their supernatants, could induce T‐cell apoptosis.117, 147 Subsequent studies revealed that TDEs isolated from culture supernatants and sera could induce the apoptosis of activated CD8+ T‐cells.