Clinical significance of longitudinal complement measurements in recipients of bone marrow transplant.

Overall activity of classical complement pathway, C3 and C4 levels, level of circulating immune complexes and concentration of serum immunoglobulins were measured in 38 patients transplanted with HLA-identical bone marrow before and after transplantation for at least 4 years. Changes of complement parameters and their association with acute and chronic GVHD and with infections were analysed. A strong association was found between the development of chronic GVHD and hypercomplementaemia measured in 16 long-term survivors. Low pre-transplantation C4 activity was found to predict the development of severe acute GVHD. These findings indicate that longitudinal complement measurements may have clinical value in BMT patients.