Polyamine oxidase-mediated killing of African trypanosomes

African trypanosomes, Trypanosoma brucei brucei, T. vivax and T. congolense, were killed when incubated in vitro with ruminant sera in the presence of exogeneous spermidine, and were non-infective for mice. Purified polyamine oxidase in the presence of spermidine-mediated similar killing of trypanosomes. The abundance of polyamine oxidase activity in ruminant sera which can react with polyamines to produce products with cytotoxic properties may explain the trypanosome killing. This system may contribute to non-specific parasite killing in vivo.