Cytokine Release Syndrome — SCE Infectious Diseases MCQ

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ModerateImmunocompromised HostCytokine Release SyndromeSCE Infectious Diseases

A 45-year-old man with relapsed acute lymphoblastic leukaemia receives CAR-T cell therapy. On day 3 post-infusion, he develops high fever (40.2°C), hypotension (BP 80/50), tachycardia, and raised CRP. IL-6 levels are markedly elevated. Blood cultures are negative. What is the most likely diagnosis?

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Correct answer: A — Cytokine release syndrome (CRS) — not infection

Cytokine release syndrome (CRS) is the most common serious adverse effect of CAR-T cell therapy, occurring in 50–90% of patients (severity varies). It is triggered by massive T-cell activation and cytokine release (particularly IL-6, IFN-gamma, TNF-alpha). It mimics sepsis clinically but blood cultures are negative. Treatment is Tocilizumab (anti-IL-6 receptor antibody) for moderate-severe CRS, and corticosteroids for refractory cases. The ID team must be involved because: (1) CRS must be distinguished from sepsis; (2) these patients are profoundly immunosuppressed and co-infection can occur.

Reference: NICE 2024 – CAR-T cell therapy; ASTCT 2019 – CRS grading consensus