Extended Data Fig. 4: T-cell responses in fresh and cryopreserved splenocytes.

Data show spot forming cells (SFC) expressing interferon gamma (IFNγ)/10⁶ splenocytes from 6 mice immunized with iPfSPZ and 6 mice immunized with mPfSPZ at 2 weeks after the fourth dose of iPfSPZ or mPfSPZ. Splenocytes from 2 mice were pooled so that there were 3 samples from each group of immunized mice (a, b, c, d, e, f and h). Each pooled splenocyte sample was assayed in duplicate and each data point represents the mean of the duplicates. Results are median and interquartile ranges of SFC/10⁶ splenocytes after incubation with stimulating cells at different concentrations. P values were calculated using the Mann-Whitney U test. The same symbol was used for each pool sample at the 3 different concentrations of stimulating cells. T-cell responses against Plasmodium falciparum-infected red blood cells (PfRBC) in fresh (a) and cryopreserved (b) splenocytes from immunized mice. One pool (●) had no detectable signal at 1x10⁵ PfRBC but had a signal at both 2x10⁵ PfRBC and 5x10⁴ PfRBC. The negative response at 5x10⁴ was considered a technical error and removed from the analysis. c, d. T-cell responses against mPfSPZ in fresh (c) and cryopreserved (d) splenocytes from immunized mice. Splenocytes were stimulated with 2.5x10⁴ mPfSPZ. The responses to incubation with vaccine diluent alone are also shown. e, f. T-cell responses against uninfected red blood cell (uRBC) in fresh (E) and cryopreserved (F) splenocytes from immunized mice. The same symbol was used for each pool at the 3 different concentrations of uRBC (2x10⁵, 1x10⁵, and 5x10⁴). g. T-cell responses against mPfSPZ in fresh splenocytes from naïve mice. Splenocytes of 2 naïve mice were pooled and frozen before assaying in duplicates and splenocytes of 2 naïve mice were pooled. and assayed fresh in duplicate. Splenocytes from naïve mice were stimulated with 2.5x10⁴ mPfSPZ. h. T-cell responses against PfRBC in fresh and cryopreserved splenocytes from naïve mice. Fresh and cryopreserved splenocytes from naïve mice were stimulated with 2x10⁵, 1x10⁵, and 5x10⁴ PfRBCs.