NONCOORDINATED BIOSYNTHESIS OF EARLY COMPLEMENT COMPONENTS IN A DEFICIENCY OF COMPLEMENT PROTEINS C1R AND C1S

We report on a 60-year-old woman with systemic lupus erythematosus and a total (95%) Clr and a partial (36%) Cls deficiency. The patient com plained about cutaneous lesions on forearms and legs without other sys temic involvement. Elevated anti-nuclear, anti-native DNA and anti-SSA antibodies were present. The finding of persistently depressed levels of haemolytic complement activity (CH50) on both serum and plasma, as sociated with normal levels of C3, C4 and C2 components, and normal al ternative pathway haemolytic activity showed a deficiency of an early component of the classical pathway. Indeed Clr component was below the limits of detection whereas Cls component was lowered (36%). The depr essed CH50 was only corrected by purified Clr. Biosynthesis of Clr and Cls by patient's monocytes was spontaneously normal but not up-regula ted by interferon-gamma for Clr alone, whereas the biosynthesis of Cls , but also of interleukin-6, was increased, indicating a specific disr egulation of Clr. The deficiency was associated with a lupus syndrome and a fatal assumed septic shock. This is in agreement with other repo rted cases.