Objective: To investigate the effect of L-arginine (L-Arg) during blood-stage infection by P.y17XL in DBA/2 mice.
Methods: DBA/2 mice were divided into 2 groups, 20 mice in each group. Mice were respectively administered with L-Arg (1.5 g/kg, L-Arg group) and normal saline (control group) 7 days before they were infected intraperitoneally by 1 x 10(6) pRBC. Parasitemia were detected by Giemsa stained thin-smear microscopy and survival rate were monitored daily. Flow cytometry was introduced to detect the subsets of splenic CD4+CD69+ T cells, F4/80+CD36+ macrophages, myeloid dendritic cells (mDCs) (CD11c+CD11b+), plasmacytoid dendritic cells (pDCs) (CD11c+B220+) on day 3, 5 post infection (p.i.). The levels of IFN-gamma and NO in the supernatant of splenocytes culture were detected by ELISA and Griess reaction, respectively.
Results: Pre-treatment of mice with L-Arg significantly decreased the parasitemia from 45% to 20% and shortened self-cure time from 22d to 20d after infection. The level of F4/80+CD36+ macrophages [(29.61 +/- 0.47)%], IFN-gamma [(485.84 +/- 39.31) pg/ml], CD4+CD69+ T cells [(7.3 +/- 0.68)%], NO [(42.51 +/- 1.32) micromol/L], mDCs(CD11c+CD11b+) [(5.51 +/- 0.87)%] and pDCs(CD11c+B220+) [(5.60 +/- 0.85)%] in L-Arg group was higher than those in control group [(36.46 +/- 1.33)%, (767.86 +/- 20.56) pg/ml, (11.27 +/- 0.97)%, (78.66 +/- 2.89) micromol/L, (10.02 +/- 0.37)%] and (9.01 +/- 0.53)%, respectively].
Conclusion: L-Arg enhances Th1 immune responses during the early stage of P.y17XL infection in DBA/2 mice via the activation of DCs.