Results of a recent study that will be shared at the 67th American Society of Hematology (ASH) Annual Meeting and Exposition in Orlando, FL from Dec. 6 to 9, showed that in patients with fetal and neonatal alloimmune thrombocytopenia (FNAIT), the antibodies that attack platelets act in different ways. This makes it hard for doctors to predict how severe the disease will be.
FNAIT happens when a pregnant woman’s immune system attacks her baby’s platelets because it sees a protein (human platelet antigen-1a, HPA-1a) derived from the father as foreign. The mother’s antibodies cross the placenta and destroy the baby’s platelets, which can cause dangerously low counts and sometimes bleeding in the brain.
While scientists know that anti-HPA-1a antibodies produced by the mother’s immune system are the main cause of FNAIT, these antibodies don’t all act the same way. Small differences in how they bind, how they are shaped, and how they function can affect how serious the disease becomes. Because of this, doctors often struggle to predict which pregnancies will be most at risk.
In a recent study, researchers examined two newly discovered anti-HPA-1a antibodies, called D-204 and M-204, taken from a patient with severe FNAIT. When they compared these antibodies to others already known, they found that M-204 behaved in a unique way. It attached differently to certain cells and to platelets, and, importantly, it was able to make platelets clump together — a process that could make the disease more dangerous.
To understand why this happened, the scientists created different versions of the antibody and performed additional tests. They discovered that M-204 triggered platelet clumping through a specific receptor called FcɣRIIa. When this receptor was blocked, the platelet clumping stopped completely.
Read more about FNAIT testing and diagnosis
“Our findings highlight the functional diversity of anti-HPA-1a antibodies and provide new insights into their pathogenic mechanisms,” the researchers said.
Understanding these differences between antibodies may help doctors better identify high-risk pregnancies and improve care for affected babies in the future.
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