Introduction Alemtuzumab, a humanised monoclonal antibody directed at CD52, is a highly active treatment for multiple sclerosis (MS) that induces rapid depetion of circulating lymphocytes. Infusion-associated reactions and autoimmune disorders are established adverse effects. We describe two cases of alemtuzumab associated allergic inflammatory syndrome involving the lungs and gallbladder in two young patients after their first course of Alemtuzumab.

Case 1 A 26 year old female with relapsing-remitting MS (RRMS) received her first course of alemtuzumab. On the fourth day of treatment, she developed bronchospasm, chest pain and an interstitial infiltrate in the right lower lobe on chest X-ray. She had right upper quadrant pain and a positive Murphy’s sign and ‘gallbladder sludge’ on ultrasound. Blood tests showed lymphopenia and eosinophilia. The patient was diagnosed with acalculous cholecystitis. Antibiotic therapy was initiated but laparoscopic cholecystectomy was required. The pathology demonstrated eosinophilic cholecystitis.

Case 2 A 29 year old man with RRMS was switched to alemtuzumab due to positive JCV antibody status. He had an episode of hemoptysis on the fifth day of the infusion. Two days later, haemoptysis was accompanied by chest tightness. Physical examination revealed a palpable liver and positive Murphy sign. Blood tests were remarkable for abnormal liver enzymes. Signs of interstitial changes in the right lower lobe were observed on a chest X-ray. The patient was diagnosed with acalculous cholecystitis and antibiotic therapy was initiated. The infiltrate resolved and the clinical signs quickly improved.

Conclusion The characteristics of this condition are acute onset (within days of alemtuzumab) and non-infective inflammation of the lung (right lower lobe in these cases) and gallbladder. The pathology in one case indicates this is likely to be a drug related, allergic phenomenon with extensive eosinophilic infiltration of the gallbladder.