FREE PROTEIN-S LEVELS ARE ELEVATED IN FAMILIAL C4B-BINDING PROTEIN-DEFICIENCY

  • 15 December 1990
    • journal article
    • research article
    • Vol. 76  (12) , 2527-2529
Abstract
In plasma, 40% of the protein S is free and functions as a cofactor for the anticoagulant effects of activated protein C. The remaining 60% of protein S is complexed to C4b-binding protein and is functionally inactive. A family with hereditary C4b binding protein deficiency has been identified with C4b-binding protein levels in an affected father and daughter of 37 .mu.g/mL and 23 .mu.g/mL, respectively, these values are significantly below the normal range for this protein of 180 .mu.g/mL .+-. 44 .mu.g/mL (mean .+-. 2 SD). The total protein S (free + bound) is normal in three individuals (23.2 .mu.g/mL and 17.8 .mu.g/mL, respectively; normal 19.1 .mu.g/mL .+-. 6.0 .mu.g/mL). The free protein S levels are markedly increased at 22.5 .mu.g/mL and 17.4 .mu.g/mL, respectively (normal 5.9 .mu.g/mL .+-. 2.4 .mu.g/mL). This epxeriment of nature shows that total protein S levels in plasma are not affected by the absence of C4b-binding protein and that chronic elevation of free protein S is not associated with increased hemorrhagic tendencies.