HUMAN-PLASMA PREKALLIKREIN (FLETCHER FACTOR) CLOTTING ACTIVITY AND ANTIGEN IN HEALTH AND DISEASE

  • 1 January 1978
    • journal article
    • research article
    • Vol. 92  (1) , 84-95
Abstract
Human plasma prekallikrein (Fletcher factor) clotting activity and antigen levels were examined in various clinical conditions. Prekallikrein antigen was measured by a newly developed, specific, and sensitive radioimmunoassay [RIA]. The assay had no demonstrable cross-reactivity with human urinary kallikrein nor, in the species tested, animal plasma prekallikrein. This assay was able to measure plasma kallikrein after its biological functions had been inactivated by plasma inhibitors. Normal human pooled plasma contained approximately 50 .mu.g/ml prekallikrein. Quantitative measurement of plasma prekallikrein was possible for concentrations as low as 0.3% of that of normal pooled plasma. A good correlation (correlation coefficient = 0.71) existed between titers of plasma prekallikrein measured by Fletcher factor clotting assays and RIA among 40 normal subjects. Both prekallikrein clotting activity and antigen were significantly reduced in plasmas of patients with advanced hepatic cirrhosis or DIC [disseminated intravascular coagulation]. Prekallikrein activity and antigen were mildly decreased in plasmas or serums of patients with chronic renal failure and nephrotic syndrome but were normal in those of patients under treatment with warfarin or suffering from SLE [systemic lupus erythematosus], rheumatoid arthritis, sarcoidosis, or HANE [hereditary angioneurotic edema]. Human cord serum contained a lower titer of prekallikrein antigen than adult serum. Strenuous physical exercise did not significantly change plasma prekallikrein levels.

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