Development of bacillus Calmette-Guérin-induced antitumor activity in peripheral blood mononuclear cells.

Peripheral blood mononuclear cells (PBMNCs) after bladder instillation of bacillus Calmette-Guérin (BCG) to patients with superficial bladder carcinoma showed lytic activity against natural killer (NK)-sensitive and NK-resistant target tumor cells. PBMNCs in normal volunteers were isolated and cultured with BCG (5 micrograms/ml) in vitro. Maximum cytotoxicity was obtained within 24 h. Cytosine arabinoside as a DNA synthesis inhibitor did not inhibit this killer cell activation. Monoclonal antibody treatment revealed that both precursor and effector cells were NK cell type. However, effector cells had a wider spectrum of target cells than usual NK cells. The recognition specificity from cold target competition experiments was selective.