PROTEIN-S DEFICIENCY IN LUPUS-ERYTHEMATOSUS SECONDARY TO HEREDITARY ANGIO-EDEMA

We report a child with lupus erythematosus secondary to type 2 heredit ary angio-oedema (HAE). Reduced levels of free protein S were found. T otal protein S, and C4 binding protein (C4bp) were normal, and there w as no evidence of anticardiolipin antibodies or lupus anticoagulant. W e postulate that reduced levels of C4, secondary to C1 inhibitor defic iency, resulted in increased binding of protein S to C4bp, leading to reduced levels of free protein S and thus functional deficiency of pro tein S.