GMA successfully removed IL-17A-producing monocytes from blood. (A) Contour plots of PBMCs that were isolated from the patient’s blood on week (w) 159 before and immediately after GMA were stained intracellularly with an anti-IL-17A antibody in combination with surface marker staining for monocytes (CD14). (B) Histograms of the cells that were trapped in the GMA column on week 159 and stained with antibodies for either IL-17A (black line) or Alexa 647 isotype (gray area). The percentage refers to IL-17A⁺ cells among PBMCs. (C) Correlation between plasma IL-17A levels and percentage of IL-17A⁺ cells trapped in the GMA column. (D) Correlation between IL-17A levels in CSF and plasma. CSF was collected 1 to 2 times per year and mostly on occasions separate from when plasma was collected; therefore, panel D includes only 5 time points: 1 time point following a long break in GMA (i), 3 time points with plasma and CSF collection at maximum 1 week apart (ii-iv), and 1 time point ≥6 months after GMA termination (v).