Induction of specific immune responses against the Plasmodium vivax liver-stage via in vitro activation by dendritic cells.

Due to chronic morbidity, the risk of increasing drug resistance and the existence of the hypnozoite stage in Plasmodium vivax malaria, there is a need to find out how hosts develop immunity to compromise the malaria parasites. Here we focused on an in vitro model for immunotherapy and vaccine development. Immunosuppressive mechanisms in malaria include inhibition of T cell response and suppression of dendritic cell function. Using in vitro activation of lymphocytes by malaria antigen-pulsed dendritic cells could overcome the limitation of antigen presentation during acute infections. Here we showed that the sporozoite-pulsed dendritic cell could elicit cytotoxicity against liver stage of P. vivax. Analysis using immunophenotypic markers showed maturation of the dendritic cells and stimulation of cytotoxic T cells. Functional assay of the in vitro-activated cytotoxic T cells showed enhancement of specific killing of the P. vivax exoerythrocytic stages within infected hepatocytes. This model may be useful for vaccine development against human malaria.