Potentiation of release of interleukin-2 by bleomycin.

The antineoplastic drug bleomycin, which has not been shown to have immunosuppressive activity, was tested for its effect on concanavalin A-induced interleukin-2 production. When the drug was added to splenocytes of Lewis rats or Balb/c mice in the presence of concanavalin A, in optimal conditions for interleukin-2 production, no detectable effects were seen. However, using a suboptimal dose of concanavalin A, bleomycin increased interleukin-2 release significantly. This effect was achieved using less than 1 microgram/ml bleomycin. In addition, bleomycin was tested for its ability to alter interleukin-1 production by peritoneal exudate macrophages. The drug seems to increase the release of interleukin-1 from peritoneal exudate macrophages of Lewis rats without any lipopolysaccharide added or with a suboptimal concentration of lipopolysaccharide. It is suggested that bleomycin, and probably other cytotoxic drugs, may modulate the immune response through its effects on the release of immunostimulating cytokines such as interleukin-1 and -2.