A 70-year-old man with CLL and a pretreatment lymphocyte count of 180 x 10^9/L receives his first dose of rituximab. Two hours into the infusion he develops fever, rigors, hypotension and hypoxia. The most likely explanation is:
- A Cytokine release syndrome from massive B-cell lysis, managed by slowing the infusion ✓
- B Anaphylaxis to murine protein requiring permanent discontinuation
- C Immune complex deposition causing serum sickness
- D Transfusion-related acute lung injury from a contaminated product
Correct answer: A. Cytokine release syndrome from massive B-cell lysis, managed by slowing the infusion
Explanation
First-infusion reactions to rituximab are caused by complement activation and cytokine release from rapid lysis of circulating CD20-positive A cells, and severity correlates directly with tumour burden. In high-count CLL the reaction can mimic anaphylaxis but is managed by stopping or slowing the infusion, supportive care, and resuming at a slower rate; premedication and split dosing reduce risk. It is not IgE-mediated anaphylaxis against murine epitopes, so it does not mandate permanent discontinuation, and serum sickness appears days later.
Reference: Katzung Basic and Clinical Pharmacology, 15th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.