A monoclonal antibody to human protein S used as the capture antibody for measuring total protein S by enzyme immunoassay.
Measurement of Protein S in human plasma is clinically important because of deficiency of this protein, which functions as a cofactor of the naturally occurring anticoagulant activated Protein C, is a risk factor for venous thromboembolism. We describe a two-site, enzyme-linked immunosorbent assay (ELISA) for measuring Protein S in which a monoclonal IgG directed against the calcium-independent conformation of Protein S is the capture antibody. The range of detection for the assay was 10 to 160 ng of Protein S per milliliter. The coefficients of variation were 4.6%-7.3% within-assay and 7.7%-10.1% between-assay. We compared this assay with an ELISA involving a polyclonal anti-Protein S rabbit IgG as capture antibody (I) and with Laurell's electroimmunoassay (II) to measure Protein S in plasma from 32 normal subjects and 121 patients or individuals expected to have low concentrations of total Protein S (full-term newborns, pregnant women after the 18th week of gestation, patients with disseminated intravascular coagulation or liver cirrhosis, patients receiving therapy with warfarin, and patients with congenital Protein S deficiency). In general, the results obtained with the monoclonal antibody-based ELISA correlated well with those from I (r = 0.94), less well with those from II (r = 0.86).
Krachmalnicoff
A
A
A Bianchi Bonomi Hemophilia and Thrombosis Center, University of Milan, Italy.
Tombesi
S
S
Valsecchi
C
C
Albertini
A
A
Mannucci
P M
PM
D000328:Adult; D000911:Antibodies, Monoclonal; D001666:Binding Sites, Antibody; D002352:Carrier Proteins / Q000097:blood; D003169:Complement Inactivator Proteins; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006023:Glycoproteins / Q000097:blood* / Q000172:deficiency / Q000276:immunology; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology; D007231:Infant, Newborn; D008297:Male; D010641:Phenotype; D011247:Pregnancy; D017293:Protein S
D000911:Antibodies, Monoclonal; D002352:Carrier Proteins; D003169:Complement Inactivator Proteins; D006023:Glycoproteins; D007074:Immunoglobulin G; D017293:Protein S