Antibody-linked immuno-sedimentation agent and method of isolating a target form a sample using same

A method of isolating a target from a sample, the method comprising:

• a) forming a mixture comprising:
• i) a sample, wherein the sample comprises a target and a non-target unwanted component, wherein the non-target unwanted component comprises a non-target antigen;
• ii) red blood cells;
• iii) an antibody-linked immuno-sedimentation agent comprising an antibody directly linked to a soluble sedimentation agent by a non-antigen binding region of the antibody, wherein the antibody is a monoclonal antibody or antigen-binding fragment thereof, and wherein the antibody specifically binds to the non-target antigen;
• and
• iv) the soluble sedimentation agent, wherein the soluble sedimentation agent is unlabeled and selected from the group consisting of polyethylene glycol, dextran, and hydroxyethyl starch;
• b) incubating the mixture of a) under conditions sufficient to form a red blood cell rouleaux complex, comprising the red blood cells, the antibody-linked immuno-sedimentation agent bound to the to the non-target unwanted component, and the unlabeled sedimentation agent;
• c) separating the red blood cell rouleaux complex of b) from the mixture by centrifugation and/or sedimentation to form a red blood cell rouleaux layer comprising the non-target unwanted component;
• d) removing the red blood cell rouleaux layer of c), thereby removing the non-target unwanted component from the mixture;
• and
• e) recovering the target from the mixture following step d), thereby isolating the target from the sample,
• wherein the sedimentation agent of iii) and iv) is present in the mixture of a) in a concentration suitable to induce the formation of the rouleaux in step (b) and to co-sediment the unwanted component into the rouleaux layer in step (c).