Rheumatoid Factor (RF) interference is a major issue when testing the performance of immunoassays. RF and other autoimmune antibodies present in the serum of Rheumatoid Arthritis patients can, presumably, bridge capture and detection antibodies in a non-specific fashion. This phenomenon leads to the generation of non-specific immunoassay signals and the recovery of higher than expected results as well as false positives. Molecular Depot’s proprietary reagent RF Interference Blocker is a Rheumatoid Factor interference suppressor consisting of a proprietary, highly concentrated, blend of anti-RF antibodies. RF Interference Blocker can be simply spiked into immunoassay reagents to a target concentration of 100-500 ug/mL. Optimal RF Interference Blocker concentration need to be established in an assay-dependent fashion.