Radical treatment in the early phase of primary infection with Plasmodium parasites with different levels of virulence and its effect on the maturation and functioning of dendritic cells during the course of reinfection

Objective To investigate radical treatment in the early phase of primary infection with Plasmodium parasites with different levels of virulence and its effect on maturation and functioning of dendritic cells(DC) during the course of reinfection.Methods DBA/2 mice were infected respectively with Plasmodium yoelii 17XL and P.yoelii 17XNL and radically treated on day 3 after infection.The mice were then respectively reinfected with homologous Plasmodium on day 90 after primary infection.The level of parasitemia was observed by means of Giemsa staining of thin blood smears,and flow cytometry was used to quantitatively analyze the percentage of MHC-Ⅱ+DC,CD80+DC,CD86+DC,CD40+DC,and activated T cells in spleen cells on days 0,1,3,and 5 post-reinfection,respectively.Results Parasitemia in radically treated mice was transient after reinfection and extremely low in the two groups of treated mice.The percentage of MHC-Ⅱ+DC,CD80+DC,CD86+DC,and CD40+DC in spleen cells of the mice all began to increase on day 3 post-reinfection.Moreover,the percentage of activated T cells began to increase steadily from day 1 to day 5 after reinfection.At each time tested,however,the levels of parasitemia and percentage of activated T cells,MHC-Ⅱ+DC,CD80+DC,CD86+DC,and CD40+DC in spleen cells in the two groups of treated mice did not differ significantly.Conclusion After radical treatment in the early phase of primary infection with Plasmodium parasites with different levels of virulence,a second challenge with virulent plasmodium caused DC to mature and function,much as a less virulent Plasmodium infection would.