Abstract
A 51chromium isotope release assay is described for measuring in vitro cytotoxicity reactions against allogeneic target cells. Lymphoid cells from some patients with localized transitional cell carcinoma (TCC) were shown to selectively lyse targets derived from two long-term cell lines of TCC. The effector cells in this reaction did not form E rosettes. Cytotoxicity was successfully recovered after cryopreservation.