Polyamine Oxidase in Human Retroplacental Serum Inhibits the Growth of Plasmodium falciparum,
WALTER REED ARMY INST OF RESEARCH WASHINGTON DC
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Human retroplacental serum RPS containing polyamine oxidase inhibited the growth of the Camp strain of Plasmodium falciparum in vitro as assayed by the parasites decreased incorporation of 3H-hypoxanthine. Inhibition was dose-dependent on the concentrations of serum polyamine oxidase and added polyamines. Almost complete inhibition was seen in 96-hr asynchronous cultures containing 10 RPS. and in those containing 1.2 RPS plus 50 microM polyamine. Subtle morphologic changes in mature stages and decreased numbers of new rings were associated with inhibition seen in 19-hr synchronous cultures initiated at the trophozoite stage. These incubation times were longer than in previous reports showing inhibition of malaria parasites by bovine polyamine oxidase but not by human polyamine oxidase. Macrophages contain polyamine oxidase, the reaction products of which are known to be similar to those RPS polyamine oxidase but different from those of bovine polyamine oxidase. It remains to be determine whether human polyamine oxidase, acting upon ubiquitous, contributes to host defenses against malaria. Keywords Antimalarials Reprints.