Monocyte monolayer assay

Monocyte Monolayer Assay (MMA) is a laboratory technique used in transfusion medicine to predict the compatibility of blood transfusions, especially in cases where patients have developed alloantibodies against donor red blood cells (RBCs). This assay assesses the ability of a patient's monocytes to adhere to and phagocytize antibody-coated RBCs under in vitro conditions, simulating the in vivo environment to some extent. The MMA is particularly useful in the management of patients with autoimmune hemolytic anemia, alloimmune hemolytic anemia, and those who have developed antibodies from previous transfusions or pregnancies.

Procedure

The Monocyte Monolayer Assay involves isolating monocytes from the patient's blood and mixing them with donor RBCs that have been coated with the patient's serum. The mixture is then incubated to allow for phagocytosis to occur. After incubation, the assay is evaluated microscopically to determine the percentage of monocytes that have ingested RBCs. A higher percentage indicates a greater likelihood of incompatibility and adverse reactions to the transfused blood.

Clinical Significance

The MMA provides valuable information for the selection of compatible blood units for patients with complex serologic problems. It helps in identifying potentially compatible units that might be missed by standard serologic techniques. This is particularly important for patients who require frequent transfusions and have developed multiple alloantibodies, making it difficult to find compatible blood units.

Advantages

• Provides a functional assessment of the clinical significance of detected antibodies.
• Can help in the identification of suitable blood units for patients with multiple alloantibodies.
• May reduce the risk of transfusion-related adverse effects in sensitized patients.

Limitations

• The assay is labor-intensive and requires specialized laboratory expertise.
• It is not widely available and is mostly used in specialized transfusion centers.
• The interpretation of results can be subjective and requires experienced personnel.

Conclusion

The Monocyte Monlayer Assay is a valuable tool in transfusion medicine, offering insights into the potential clinical significance of alloantibodies against donor RBCs. Despite its limitations, the MMA plays a crucial role in the management of patients with complex transfusion needs, helping to ensure the safety and efficacy of blood transfusions.