New functional assays for assessing hemolytic activity in intravenous immunoglobulin (IVIG) products could improve safety for patients, especially those at higher risk for complications such as fetal and neonatal alloimmune thrombocytopenia (FNAIT), according to an article published recently in Blood.
The Complement-Dependent Hemolysis Assay (CDHA) was developed to better evaluate intravascular hemolysis, and the Monocyte Monolayer Assay (MMA) was developed to better evaluate extravascular hemolysis, both offering more accuracy than existing methods. These advancements could potentially reduce severe complications such as anemia, renal failure, and even death, which are rare but serious risks of IVIG therapy.
“The CDHA and MMA may be useful for investigation of clinically hemolytic lots, and to increase understanding of product and patient risk factors,” the authors of this study wrote.
Hemolysis occurs in approximately 1.6% of patients receiving IVIG, particularly in non-O blood group individuals treated with high doses. It can result from the presence of antibodies to blood groups A and B, which may inadvertently remain in IVIG products during manufacturing. Current guidelines set limits on anti-A and anti-B levels, but hemolysis events persist, possibly due to manufacturing changes that increase isoagglutinin content.
To address this, researchers developed the CDHA to model intravascular hemolysis and adapted the MMA to measure extravascular cell-mediated hemolysis. In the MMA, macrophages differentiated into M1 and M2 subtypes were exposed to red blood cells coated with IVIG or control substances. Results showed that M2 macrophages demonstrated greater hemophagocytic activity than M1 cells. Meanwhile, the CDHA evaluated complement-dependent lysis of red blood cells.
Read more about FNAIT treatment and care
These new assays were compared with the Direct Hemagglutination Test, a European Pharmacopeial method currently used to assess hemolytic potential. Seven investigational IVIG products were tested, and the CDHA and MMA identified hemolytic activity in certain lots that met the Direct Hemagglutination Test standard. These results suggest that the functional assays offer a more reliable assessment of hemolytic risk in IVIG products.
For patients, especially those requiring IVIG for autoimmune or immunodeficiency conditions, these advances could translate into reduced risks of severe hemolytic events. Improved screening of IVIG products may help prevent complications, ensuring safer and more effective treatments.
The adoption of CDHA and MMA has the potential to refine manufacturing processes and improve regulatory oversight. By identifying high-risk IVIG lots more precisely, these assays could protect vulnerable populations while enhancing understanding of product safety and patient-specific risk factors.
