Figure 3. Siltuximab but not tocilizumab reverses Teff resistance to Treg-mediated suppression.

Expanded allogeneic Tregs from a healthy control donor were cocultured at a ratio of 1:4 with Teffs from either siltuximab-treated or tocilizumab-treated patients with T1D in the presence of anti-CD3/anti-CD28–coated beads for 2 days. The percentage of suppression was determined by measuring the frequency of activated CD25⁺CD134⁺ Teffs. Each line represents an individual patient; n = 10 for siltuximab and n = 9 for tocilizumab. (A) Percentage suppression for siltuximab-treated patients and tocilizumab-treated patients. (B) Linear regression for siltuximab cohort showing positive correlation between peak drug concentration on d1 and percentage suppression at d14. (C) Percentage suppression for cohort that participated in both studies (n = 5); note these individuals are also included in A and B. Statistical tests: (A and C) Wilcoxon matched-pairs signed-rank test; (B) linear regression.