Blood tests for complement proteins, which are part of the immune system and help fight infections, could potentially be used to diagnose primary biliary cholangitis (PBC), predict the risk of developing PBC and spot patients who may develop serious liver damage, according to a recent study published in the European Journal of Medical Research.
Doctors currently do not have very reliable tools to diagnose PBC early or to predict how quickly it will get worse. The researchers wanted to find better biomarkers — special molecules in the blood that can help diagnose or predict a disease.
The study found that certain complement proteins — especially CR1, C1QA, C1QL2 and C7 — were much higher in people with PBC and could potentially be used to diagnose the disease.
Some complement proteins, like CR1, also helped predict how severe the disease might become. In fact, CR1 did a better job predicting serious liver problems than commonly used tests such as the Fibrosis-4 (FIB-4) score.
“Importantly, these results reveal the complement system not as a passive bystander but as an active participant in PBC pathogenesis, potentially driving disease progression through non-classical pathways and local immune responses,” the researchers said.
Read more about PBC testing and diagnosis
The study used data from the UK Biobank, which contains health and blood information from hundreds of thousands of people. The researchers studied blood samples from 44 people with PBC and compared them to samples from people without the disease.
The researchers also found that high levels of proteins such as CR1, CR2, C1QA, C1QL2 and C7 were linked to a greater chance of developing PBC in the future.
Meanwhile, low levels of other proteins, like C5 and C1RL, were linked to worse health outcomes in people with PBC. The researchers think that as PBC gets more advanced, the immune system may become weaker, which may cause liver function to get worse.
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