Cytokine serum levels of interleukin (IL)–6 (A.a), tumor necrosis factor (TNF)–α (A.b), IL-1β (A.c), interferon (IFN)–γ (A.d), and IL-10 (A.e) during alemtuzumab infusion cycle are presented. Cytokine levels in cultured cell supernatants: IFN-γ (B.a), IL-17A (B.b), IL-2 (B.c), TNF-α (B.d), and IL-10 (B.e) after ex vivo Cytostim stimulation and IL-6 (C.a), TNF-α (C.b), IL-1β (C.c), and IL-10 (C.d) after ex vivo LPS stimulation are depicted. Analysis was performed before infusions started (A), after methylprednisolone (B), and after alemtuzumab (C) each of the 5 infusion days (day 1–day 5 [D1–D5]). Arrowhead indicates administration of methylprednisolone, arrow indicates administration of alemtuzumab. Mean values ± SEM are presented. Asterisks indicate a statistically significant difference (*p < 0.05, **p < 0.01, ***p < 0.001).