Abstract

Alemtuzumab has recently been licensed in several countries for relapsing multiple sclerosis. Despite its marked clinical efficacy it is associated with acquired autoimmune disease with a particular predilection for the thyroid gland. Despite the recognition and surveillance mechanisms that exist to monitor patients treated with alemtuzumab, vigilance must be maintained to monitor for less common immune-related disorders. We present two patients diagnosed with hypersensitivity pneumonitis following alemtuzumab therapy for multiple sclerosis. Both patients presented with a sub-acute pulmonary illness characterized by cough and breathlessness with interstitial pulmonary infiltrates subsequently demonstrated on chest x-ray and computed tomography of the thorax. Both patients responded well to oral prednisolone and in the case of one patient for whom serum avian precipitins had been strongly positive, removal of a pet parrot. There has been no recurrence of respiratory disease following treatment. Autoimmune disease post-alemtuzumab treatment tends to be due to an aberrant humoral immune response such as that seen in Grave's disease. However, these cases highlight that cell-mediated autoimmunity disorders may also occur and underline the importance of long term surveillance for immune complications in patients treated with this drug.