Exploration du complément : actualités 2012

The complement system plays an important role in defence of the host against infection and in the clearance of immune complexes. Investigation of complement is useful for diagnosis and following of auto-immune diseases as systemaic lupus erythematosus and to identify susceptibility factors for infections in particular meningococcal and pneumococal ones. The CH50 and the AP50 tests (classical and alternative pathway 50 respectively) assesses the overall function of the classical, alternative and terminal pathway. For the patient being evaluated for the first time the measurements of plasma CH50, C3 and C4 levels is recommended. Monitoring these three biomarkers is frequently sufficient to determine the activations status and to screen complement deficiency. Several specialized approaches are available to identify which complement component is missing. The molecular characterization of the deficiency confirms the diagnosis and should be proposed to all patients. If the link between alternative pathway complement deficiencies and infections is well known, their roles in the pathogenesis of ultra rare kidney diseases as atypical hemolytric uremic syndrome or common disease as age related macular degeneration appeared recently due to the progress in genetic analysis. The goal of the complement investigations in 2012 is to homogenize the techniques in order to follow the recommendations of the accreditation process, to select biological tests useful for the patient's management and to integrate the genetics in the disease diagnosis.