Fig 2: HA118-132-specific CD4 T cells are highly activated and proliferate upon vaccination and the individual dynamics are associated with vaccination history.a–c Expression of CD127, Ki67, and ICOS+CD38++ on HA118-132-specific CD4 T cells at the indicated time points. Responses are subgrouped by vaccination history. The summary plot shows the median with 95% confidence interval within the three subgroups (for CD127 and ICOS+CD38++: BL, day 7–day 28 n = 21, day 4 n = 19; Ki67 BL—day 28 n = 11). One symbol represents response at the indicated time point. Representative dot plots in b, c show an example for a vaccine-naive donor (red) and a successive vaccinated donor (blue), gray points show the bulk population. d Spearman correlation of ICOS, CD38 co-expressing HA118-132-specific CD4 T cells at day 4 with frequency (FC) of HA118-132-specific CD4 T cells at day 4. e Expression dynamics of markers during HA118-132-specific CD4 T cell responses (n = 21). Heatmap coloring represents the z score of every marker (MFI) calculated among the time points of an individual donor response. Responses are aligned according to vaccination history. a–c Two-tailed Wilcoxon matched-pairs signed rank test with Bonferroni correction was used for multiple between-group comparisons. All time points were compared to BL. A p value of 0.0125 was considered statistically significant. **p < 0.01, ***p < 0.001, ****p < 0.0001. d Two-tailed Spearman correlation test with a confidence interval of 95%. *p < 0.05.

Fig 3: MGD019 Provides Dual Checkpoint Blockade In Vivo(A and B) Cynomolgus monkeys (5 females and 5 males per group) were infused with 10, 40, or 100 mg/kg MGD019 at days 1, 8, 15, and 22. Mean serum concentrations of MGD019 and mean percentages of PD-1+ cells with MGD019 detectable at cell surface by flow cytometry are shown. Error bars depict SEMs, vertical dotted lines indicate dose administration, and the horizontal dotted line marks 100% cell-surface binding.(C–E) Splenocytes obtained from cynomolgus monkeys treated with 4 weekly administrations of MGD019 or vehicle control and necropsied 3 days after the last infusion were stained for CD28/CD95 (C), ICOS (D), or CD25/FoxP3 (E) expression. Means and SDs are shown. Gated on CD45+/CD3+/CD4+ cells.(F) Cynomolgus monkeys were infused i.v. Q1W for 3 weeks with 75 mg/kg MGD019 (3 males/3 females) or, in a separate study, 100 mg/kg parental PD-1 mAb (2 males/2 females). Ki67 expression on circulating CD4+ T cells was quantified by flow cytometry. Means and SEMs are depicted.See also Figure S5.