Increased mTOR signaling at baseline and upon stimulation with IL-6. PBMCs from 8 healthy donors and 8 iMCD-TAFRO patients in remission were left untreated, treated with 25 ng/mL IL-6, or treated with IL-6 and the JAK inhibitor ruxolitinib (1μM). (A-C) Kinetics of IL-6–mediated phosphorylation of S6 protein in CD14⁺ monocytes (A), CD4⁺ T cells (B), and CD8⁺ T cells (C) from healthy donors (blue) and iMCD patients in remission (red). Mixed analysis of variance analysis of the center-log-transformed proportions (compositional analysis) yielded that the proportion of pS6⁺ cells is higher for CD14⁺ monocytes (P = 6.0 × 10⁻⁸), CD4⁺ T cells (P = 4.6 × 10⁻⁷), and CD8⁺ T cells (P = 4.2 × 10⁻⁶) across the time measurements in iMCD compared with healthy controls. Compositional analysis specific to each time was also calculated using unpaired 1-tailed Mann-Whitney U tests, and the significance is denoted in panels A-C by asterisks. (D-F) Paired comparison of the frequency of pS6⁺ monocytes, CD4⁺ T cells, and CD8⁺ T cells at 0 minutes (black) and 120 minutes of stimulation with IL-6 for iMCD patient (red) and healthy donor samples (blue). P values from Wilcoxon signed-rank test on the transformed proportions. Since there is a <1% probability that 2 events with <.05 (individual type I error) occurs twice in only the subjects and not the controls, the results were considered statistically significant without a need for P-value adjustment approximations. (G-I) Paired comparison of the frequency of pS6⁺ monocytes (G), CD4⁺ T cells (H), and CD8⁺ T cells (I) following treatment with IL-6 alone or following treatment with IL-6 and the JAK inhibitor, ruxolitinib, for iMCD patient and healthy donor samples. *P < .05, **P < .01 by Wilcoxon signed-rank test. ns, not significant.