Figure 4. Therapeutic ligation of OX40 during acute Plasmodium infection enhanced both Th1- and Tfh-like recall responses and per cell protective capacity of memory CD4 T cells.
(A) Experimental design. Mice were infected with 1×106 Py and administered either control rIgG or α-OX40 antibodies on day 7 and 10 p.i. On 75 day p.i., memory CD4 T cells were sorted and transferred (2×105) into groups of Tcrα−/− mice. Recipients were challenged with P. yoelii and parasite growth kinetics were measured. Cells were analyzed on day 14 p.i. Statistical analyses (*p<0.05) reflect comparisons between recipients of memory cells from rIgG- and α-OX40-treated donor mice.
(B,C) Kinetics of parasite growth (B) and summary data (C) showing parasitemia on day 14 p.i.
(D–F) Proportions of donor-derived CD4 T cells expressing either Ly6C (D), IFN-γ (D,E), or CXCR5+PD1+ Tfh cells expressing Bcl-6 (F).
(G) Total number of CXCR5+PD1+Bcl-6+ Tfh cells recovered from recipients.
(H) MSP119-specific serum antibody titers in mice seeded with memory CD4 T cells derived from rIgG- and α-OX40-treated donors.
Data (Mean +/− SEM) in (B,C,E,G,H) are pooled from 2 independent experiments with 3–4 mice/group per experiment and were analyzed using either one-way ANOVA (B,C) or Student’s t tests (E,G,H). *p<0.05 **p<0.01. N.S. = not significant. See also Figure S4.