Functional determination of C1 esterase inhibitor in fractions derived from plasma.
A traditional esterolytic assay, a commercial chromogenic assay and an in-house chromogenic assay were compared for suitability in estimating C 1 esterase inhibitor (C 1 INH) activity in plasma and fractions obtained during preparation of a clinical concentrate of C 1 INH. The esterolytic and both of the chromogenic assays showed similar C 1 INH activity in unfractionated plasma samples. However, the esterolytic assay was significantly influenced by the buffer pH and concentration in fractionated plasma samples, and this often resulted in a significant overestimation of C 1 INH in some fractions. Similarly, the commercial C 1 INH assay kit did not always reliably estimate C 1 INH activity in fractions derived from plasma. A modified in-house functional assay was found to be more reliable in measuring C 1 INH in fractionated plasma samples. There was a good correlation between this activity assay and immunological assay estimates of C 1 INH in fractions derived from plasma.
Benny
A G
AG
Auckland Regional Blood Service, Auckland Hospital, New Zealand.
Brimer
C M
CM
D003174:Complement C1 Inactivator Proteins / Q000032:analysis*; D006801:Humans; D007118:Immunoassay; D011933:Reagent Kits, Diagnostic; D014443:Tyrosine / Q000031:analogs & derivatives
D003174:Complement C1 Inactivator Proteins; D011933:Reagent Kits, Diagnostic; D014443:Tyrosine; C007651:ethyl N-alpha-acetyl-tyrosinate