Biomaterial Database

Immunoassay of human platelet factor 4(PF4, antiheparin factor) by radial immunodiffusion. 1976

S Niewiarowski, and C T Lowery, and J Hawiger, and M Millman, and S Timmons

Human platelet factor 4 antigen (PF4 antigen) was measured in platelets and in plasma by means of single radial immunodiffusion. Anti-PF4 antibody obtained in rabbits by injecting highly purified human PF4 was monospecific in double immunodiffusion and in quantitative "rocket" immunoelectrophoresis. A high degree of correlation was observed between the precipitation zones in the radial immunodiffusion method and the amount of purified PF4 (in the range of 0.6 to 50.0 mug per milliliter) or the number of platelets in plasma (in the range of 5 x 10(6) to 1.6 x 10(8) platelets per milliliter applied. The sensitivity of the method was 30 to 125 times higher as compared with clotting assay (antiheparin activity) and the standard error of the method was 2.3 per cent. The method was specific for the antigen present in platelets since human leukocytes and erythrocytes gave negative results. Release of PF4 antigen from washed platelets challenged with thrombin, collagen, ADP, and antigen-antibody complexes was measured by the radial immunodiffusion assay. It usually paralleled the release of 3H-serotonin but PF4 antigen was a more sensitive marker for platelet release reaction. Release of PF4 antigen was usually 2 to 4 times higher than release of the antiheparin activity as measured by clotting assay when both were compared as percentage of total content in platelets. The level of PF4 antigen was determined in platelet-rich plasma (PRP) and platelet-free plasma (PFP) obtained from 12 healthy volunteers. While the mean level of extraplatelet pool of PF4 antigen in PFP was 0.72 +/- 0.92 mug per milliliter, PRP contained 80 +/- 22 mug of PF4 antigen per 10(9) platelets. Addition of thrombin (1 U. per milliliter) liberated all of the PF4 antigen (78 +/- 24 mug) present in PRP but ADP (50 muM) released only 31 +/- 22 mug of PF4 antigen per 10(9) platelets. The presence of heparin did not interfere with the assay of intraplatelet or extraplatelet PF4 by single radial immunodiffusion. The method described represents a simple, sensitive, quantitative, and specific assay for human PF4 antigen possessing antiheparin activity.

UI	MeSH Term	Description	Entries
D007118	Immunoassay	A technique using antibodies for identifying or quantifying a substance. Usually the substance being studied serves as antigen both in antibody production and in measurement of antibody by the test substance.	Immunochromatographic Assay,Assay, Immunochromatographic,Assays, Immunochromatographic,Immunoassays,Immunochromatographic Assays
D008297	Male		Males
D008875	Middle Aged	An adult aged 45 - 64 years.	Middle Age
D010974	Platelet Aggregation	The attachment of PLATELETS to one another. This clumping together can be induced by a number of agents (e.g., THROMBIN; COLLAGEN) and is part of the mechanism leading to the formation of a THROMBUS.	Aggregation, Platelet
D010978	Platelet Factor 4	A CXC chemokine that is found in the alpha granules of PLATELETS. The protein has a molecular size of 7800 kDa and can occur as a monomer, a dimer or a tetramer depending upon its concentration in solution. Platelet factor 4 has a high affinity for HEPARIN and is often found complexed with GLYCOPROTEINS such as PROTEIN C.	Antiheparin Factor,CXCL4 Chemokine,Chemokine CXCL4,Heparin Neutralizing Protein,PF4 (Platelet Factor 4),gamma-Thromboglobulin,CXCL4, Chemokine,Chemokine, CXCL4,gamma Thromboglobulin
D001779	Blood Coagulation Factors	Endogenous substances, usually proteins, that are involved in the blood coagulation process.	Clotting Factor,Coagulation Factors,Blood Coagulation Factor,Clotting Factors,Coagulation Factor,Coagulation Factor, Blood,Coagulation Factors, Blood,Factor, Coagulation,Factors, Coagulation,Factor, Blood Coagulation,Factor, Clotting,Factors, Blood Coagulation,Factors, Clotting
D001792	Blood Platelets	Non-nucleated disk-shaped cells formed in the megakaryocyte and found in the blood of all mammals. They are mainly involved in blood coagulation.	Platelets,Thrombocytes,Blood Platelet,Platelet,Platelet, Blood,Platelets, Blood,Thrombocyte
D003094	Collagen	A polypeptide substance comprising about one third of the total protein in mammalian organisms. It is the main constituent of SKIN; CONNECTIVE TISSUE; and the organic substance of bones (BONE AND BONES) and teeth (TOOTH).	Avicon,Avitene,Collagen Felt,Collagen Fleece,Collagenfleece,Collastat,Dermodress,Microfibril Collagen Hemostat,Pangen,Zyderm,alpha-Collagen,Collagen Hemostat, Microfibril,alpha Collagen
D005260	Female		Females
D005779	Immunodiffusion	Technique involving the diffusion of antigen or antibody through a semisolid medium, usually agar or agarose gel, with the result being a precipitin reaction.	Gel Diffusion Tests,Diffusion Test, Gel,Diffusion Tests, Gel,Gel Diffusion Test,Immunodiffusions,Test, Gel Diffusion,Tests, Gel Diffusion