Bestatin treatment and the peripheral lymphocyte population in cancer patients

Bestatin, a substance produced by Streptomyces olivoreticuli, inhibits certain cell-membrane-associated enzymes and has been shown to augment immune responses in experimental animals. We have determined whether bestatin medication changed the peripheral lymphocyte population in 15 advanced cancer patients. After 2 weeks of daily, 30 mg oral bestatin medication, the lymphocyte counts remained essentially unchanged, but the frequency of E-rosette-forming lymphocytes increased. In vitro stimulation of the lymphocytes with PHA or PPD remained essentially unchanged while the natural-killer activity of the lymphocyte population increased in most patients. Bestatin treatment caused no detectable side effects.