Abstract: A method for the rapid separation of Dirofilaria immitis immune complexes in a sample of blood or bodily fluid from an animal infected with Dirofilaria immitis preparatory to assaying for the presence of circulating parasite antigens of Dirofilaria immitis involves the steps of (a) lowering the pH of the sample to below 3.0 to effect the separation of circulating parasite antigens of Dirofilaria immitis from antibodies therefor in the sample; (b) heating the sample to a temperature within the range of approximately 56.degree. C. to 90.degree. C. for a sufficient period of time to denature the separated antibodies; and (c) increasing the pH of the resulting sample to within the range of approximately 7 to 8 to produce a sample which may be assayed for the presence of circulating parasite antigens of Dirofilaria immitis without interference from the separated antibodies.

Abstract: Radioimunoassay methods for determining the concentration of fibrinopeptide A in plasma, anticoagulation reagents for use in such methods and package test kits containing the reagents for use in such methods are provided.

Abstract: A double antibody radioimmunoassay method for determining antigens in a sample wherein polyethylene glycol is provided in a reaction medium to accelerate an immunoprecipitation reaction between water-soluble first antibodies bound to antigen and water-soluble second antibodies which are not specific to said antigens but which are specific to said first antibodies. A double antibody, multi-component radioimmunoassay test kit is also provided. The kit contains radiolabeled antigen reagent, first water-soluble antibody reagent and second water-soluble antibody reagent, as well as a polyethylene glycol reagent, which may optionally be combined with the second antibody reagent, in an amount sufficient to accelerate an immunoprecipitation reaction, between said first and second reagents.

Abstract: A method and reagent for counteracting lipemic interference in an assay of a lipid-containing sample, e.g. blood. The method includes the steps of: (a) mixing with the sample prior to or during said assay a high surface area, finely-divided adsorbent having an affinity for lipids, and a nonionic, water-soluble polymer, and (b) precipitating adsorbed lipids in said sample. The reagent includes a high surface area finely-divided adsorbent, and a nonionic, water-soluble polymer having a molecular weight of from about 1,000 to 100,000.