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Best-Selling Products
May 15 2020


Product Name

Cat. No.



Active Blocker 




Polymerized Blocker






Interferences in IVD Assays

Endogenous antibodies or other binding immunoglobulins in patient samples easily interfere with in vitro diagnostic reagents and are known as immunoassay interferences. Interferences mainly happen in double-antibody sandwich assays, competitive assays and lgM capture assays. Immunoassay interferences are mainly caused by heterophilic antibodies (HA), which can change the binding ability of the target analytes or antibody from test kits, resulting in false-positive or false-negative results, ultimately causing the test results to be inconsistent with the actual clinical conditions.

Blockers are bioactive reagents that can be used to eliminate or reduce interferences in immunoassays. Using Blockers can effectively reduce false-positive or false-negative results in immunoassays. From Genstars Biotech, we are mainly offering two types of Blockers to help our IVD partners to improve the test performance and lower the costs, which are Active Blocker (HBR-5) and Polymerized Blocker (HBR-7).



Figure 1: Schematic Representation of Mechanisms of 2 types of Blockers from Genstars Biotech  


Choose Our Blockers for IVD Assays 

Active Blocker (HBR-5) consists of antibodies derived from mouse. Specific binding site on Active Blocker can directly binding with all types of heterophilic interferences including human anti-mouse antibodies (HAMA) and Rheumatoid Factor (RF). Active Blocker works efficiently in low concentration, which minimize the reduction of sensitivity in tests caused by blocking reagents.   

Recommended concentration: Active Blocker shall be added into the sample or conjugate diluent in ELISA/CLIA at the concentration range from 0.15mg/ml to 0.6mg/ml. For LF, Active Blocker can also be applied into the sample pad. The optimal concentrations shall be determined based on your specific tests and testing systems.   


Polymerized Blocker (HBR-7) consists of crosslinked mouse IgG. When Polymerized Blocker (HBR-7) used in excess concentration, they can provide alternate binding sites for interfering antibodies. Mouse IgG can only block the interferences from HAMA.

Recommended concentration: Polymerized Blocker shall be added into the sample/ conjugate diluent in ELISA/CLIA or sample pad in LF. And at least 10 times the concentration of the MAb/PAb being utilized in the assay. The optimal concentration shall be determined based on your specific tests and testing systems.   



Genstars Biotech Co., LTD