Campath 1-H (Alemtuzumab) is a humanised monoclonal antibody which targets the 
CD52 antigen, a low molecular weight glycoprotein present on the surface of most 
lymphocyte lineages, causing complement mediated lysis and rapid and prolonged T 
lymphocyte depletion. Following encouraging initial data from other centres we 
report our open label experience of using Campath 1-H as a treatment in 
aggressive relapsing multiple sclerosis in a consecutive series of 39 highly 
selected patients treated across three regional centres and followed for a mean 
of 1.89 years. The mean annualised relapse rate fell from 2.48 pre treatment to 
0.19 post treatment with 29% of documented relapses observed in the 12 weeks 
following initial infusion. Mean change in EDSS was -0.36 overall and -0.15 in 
those patients completing > or =1 year of follow- up. Eighty-three per cent of 
patients had stable or improved disability following treatment. Infusion related 
side effects were common including rash, headache and pyrexia but were usually 
mild and self limiting. Transient worsening of pre-existing neurological 
deficits during infusion was observed in 3 patients. 12 patients developed 
biochemical evidence of autoimmune dysfunction, 2 patients developed thyroid 
disease and 1 patient autoimmune skin disease. We conclude that relapse rates 
fall following Campath 1-H. Whilst side effects were common these were normally 
self limiting or easily managed, suggesting Campath 1-H may be of use in the 
treatment of very active relapsing remitting multiple sclerosis.