Complement in acute leukaemia: its role in infection

This study determines the frequency of complement system dysfunction in adult patients with acute myeloid leukaemia and its prognostic significance. Twenty four patients with acute leukaemia had complement studies performed at time of presentation and during the haematological trough occurring between 7 and 14 days after the administration of chemotherapy. At presentation 32% of patients had abnormal complement function. Only 54% of patients maintained normal complement activity throughout the period of remission induction. The aetiology of the disturbance is unclear and no single causative factor was determined. Patients with abnormal complement function had significantly greater morbidity from infection during the period of remission induction as measured by the number of febrile (greater than 38 degrees C) days (p less than 0.05), and were more likely to have pathogens isolated by blood culture during septic episodes (relative risk 4.0, p less than 0.01). These findings show a significant increase in morbidity associated with depressed complement function and emphasise the important role the complement system plays in maintenance of host defences.