Mechanism of heparin interference in detection of LIAISON® Rubella IgM

To investigate the effects of heparin in detection of LIAISON® Rubella IgM (Rub-M) and the mechanism of interference.

Different concentrations of lithium heparin and sodium heparin were added to ten serum samples. The relative light units (RLU) value of Rub-M was measured using the LIAISON XL detection system. Different levels of IgM serum were incubated with magnetic particle in Rub-M detection kit at 4 °C for 4 h, blocking anti-human IgM-specific antibodies coated on the surface of magnetic particle. Separately, the rubella virus antigen in Rub-M detection kit was replaced by phosphate-buffered saline (PBS). The RLU values of LIAISON® Rub-M of original serum and serum containing various concentrations of heparin were measured after the above two different treatments.

The RLU value of LIAISON® Rub-M increased with the increase of heparin content lower than 40 IU/mL, and reached a peak value at 40-50 IU/mL. The RLU value of LIAISON® Rub-M then decreased with the decrease of heparin concentration. When rubella virus antigen was replaced by PBS, the RLU value of LIAISON® Rub-M of serum samples containing 40 IU/mL heparin decreased significantly. The blocking concentration of IgM increased gradually, and the RLU value of LIAISON® Rub-M of seven serum samples containing 40 IU/mL heparin also decreased gradually.

Plasma with heparin cannot be used to the detection of LIAISON® Rub-M. Heparin may participate in the reaction by binding with rubella virus antigen and anti-human IgM-specific antibodies coated on the surface of magnetic particle, thus affecting the detection results.