ST2 blockade decreases numbers of LCMV-specific effector CD8⁺ and CD4⁺ T cells in FHL2 mice. WT and Prf1^−/− mice were infected with LCMV, treated with either α-ST2 antibodies (open circles) or control antibodies (closed circles), and assessed on day 8 p.i. Analyzed by linear mixed-effects model to account for baseline variability between experimental replicates: treatment and genotype were modeled as fixed effects, and experiment was treated as a random effect (eg, intercept only). The number symbol indicates significance of genotype (WT vs Prf1^−/−); the paragraph symbol indicates treatment (control vs α-ST2); and the asterisk indicates interaction between genotype and treatment. Representative flow plots gated on live CD90.2⁺CD8⁺ T cells (A) or CD90.2⁺CD4⁺ T cells (C), showing effector/memory phenotyping by CD44 and CD62L expression. Numbers of splenic CD44^hiCD62L^loCD127^lo effector CD8⁺ T cells (B) or CD4⁺ T cells (D). Data pooled from 4 independent experiments, n = 17 to 18 mice per group. (E) Representative flow plots gated on live CD90.2⁺CD8⁺ T cells, showing gp33 major histocompatibility complex (MHC) class I tetramer (tetr) staining. (F) Numbers of splenic gp33-specific CD8⁺ T cells (n = 13-14 mice per group, data pooled from 3 independent experiments). (G) Representative flow plots gated on live CD90.2⁺CD4⁺ T cells, showing gp66 MHC class II tetramer staining. (H) Numbers of splenic gp66-specific CD4⁺ T cells (n = 9-10 mice per group, data pooled from 2 independent experiments). *P < .05; ^§§§P < .001; ^##P < .01; **P < .01; ^§§P < .01; ^###P < .001.