RESUMO
We investigated the effects of dexamethasone (Dx) on the proliferation of Plasmodium falciparum Indochina-I/CDC in squirrel monkeys (Saimiri sciureus boliviensis). Three splenectomized squirrel monkeys each received 16 perioral Dx doses (three times per week for 36 days), at three different dosages (0.2, 0.5, and 2.0 mg/ kg). Each monkey was intravenously inoculated with 7.8 x 10(7) red blood cells infected with P. falciparum 1 week after the initiation of Dx treatment. Parasite growth was suppressed in DX-treated monkeys in a dose-dependent manner. To determine whether this suppression of parasite development was mediated by host immunity, P. falciparum was cultured in vitro in the presence of Dx. The development of P. falciparum was also markedly suppressed in vitro by Dx treatment in a dose-dependent manner. These results suggest that Dx has a direct suppressive effect on the proliferation of P. falciparum both in vivo and in vitro, via a mechanism that is not mediated by an immunological reaction of the host.
