Fig. 7

Adoptively transferred CD4 T cells from PMIF-immunized mice confer protection to challenge by iRBCs. a BALB/cJ mice immunized with replicons encoding Con RNA or PMIF RNA were infected with 10⁶ PbAWT iRBCs and treated with chloroquine on days 7–12. Four weeks later, the mice were reinfected with 10⁶ PbAWT iRBCs and splenocytes isolated 7 days after infection, incubated with chloroquine to eliminate blood-stage parasites, and labeled with CFSE. Purified CD4⁺CD45.2⁺ T cells (2 × 10⁷) then were transferred into naïve congenic CD45.1 BALB/cJ hosts and the mice infected 3 days later with 10⁶ PbAWT iRBCs. b Frequency of iRBCs in mice adoptively transferred with CD4 T cells from Con (white circle) or PMIF (black circle) RNA immunized mice. Results are from two separate experiments. Bars represent the mean of 6 mice ± SD; *p < 0.05, ^#p < 0.001 by two-way ANOVA. c Representative CFSE dilution histogram of adoptively transferred CD4⁺ T cells (CD45.2) from donors immunized with Con or PMIF RNA and enumeration of recovered CD45.2 CD4⁺ T cells, and d proliferative response of transferred CD4 T cells into CD45.1 recipients 7 days after infection. e Percentage of proliferating CD45.2⁺ CD4⁺ T cells (CFSE^lo) producing IFN-γ after stimulation ex vivo with iRBC lysates in the presence of Brefeldin A. f Mean fluorescence intensity of PD-1 in PbAWT responsive CD45.2⁺ CD4⁺ T cells (CFSE^lo) from Con or PMIF RNA immunized donors. Results are from two separate experiments. Bars represent the mean of 8 mice ± SD; *p < 0.05, **p < 0.01 by two-tailed Mann–Whitney test