Restoration of E-rosette formation by bestatin in patients with bladder cancer.

Incubation of peripheral blood lymphocytes from patients with bladder cancer in bestatin (specific inhibitor of aminopeptidase B and leucine aminopeptidase) solution resulted in a significant increase in the proportion of E-rosette-forming lymphocytes. The increase in the proportion of E-rosette-forming lymphocytes was abolished after reincubation with 100% autochthonous serum. The fraction of E-rosette-forming lymphocytes from patients with bladder cancer which had restored receptors for sheep erythrocytes (SRBC) by incubation with bestatin also expressed receptors for the Fc portion of IgG and IgM. The proportion of EAC-forming lymphocytes remained unchanged after the incubation with bestatin. When 600 mg of bestatin was administered for 1 day to patients with bladder cancer, restorative effect on the proportion of E-rosette forming lymphocytes was also demonstrated. The proportion of EAC-forming lymphocytes, however, did not change significantly.