There is no single diagnostic blood test for PSC. This means that doctors need to piece together clues from our medical history, blood tests, symptoms and scans to make a diagnosis. To diagnose small duct PSC, a liver biopsy is required. A liver biopsy is an invasive procedure that takes very small samples of liver tissue for investigation (about 1/50,000th of the liver). This means there is sometimes uncertainty about a PSC diagnosis, especially in those with milder disease resulting in significant delays (sometimes years) in confirming the diagnosis. This causes increased stress and anxiety for those affected and vital monitoring for cancers and complications can be missed.

A simple diagnostic blood test for PSC is urgently needed

PSC is caused by an overactive immune system resulting in the production of immune cells which infiltrate the liver and colon, causing scarring and damage.  Results from genetic studies in PSC suggest that this is caused by a specific antigen, activating the immune system.

At present, we do not know which antigen the immune system this is. However, it is likely to be a protein made by the bile ducts and colon. In other conditions, where the antigen is known, simple blood tests are effective and highly accurate in providing a diagnosis, for example blood tests for anti-TTG in coeliac disease, anti-PDH in PBC and CP P in rheumatoid arthritis. Thus, identifying the antigen responsible will help us develop a PSC blood test.

In addition, not knowing the PSC antigen prevents us from deeper investigation of the immune system using brand new and exciting scientific tools which could lead to the development of new medicines to treat PSC.

In this study, funded by PSC Support, Dr Rushbrook and Dr Goode screened the blood of people with PSC to see if there was an antibody (protein made by immune cells) that is not present in people without PSC.

The samples that were screened were kindly provided by Dr Culver from Oxford University Hospitals. The scientific work was conducted by a specialist laboratory in Cambridge to ensure that the science undertaken on these samples was as accurate as could be. They also provided high level statistical analysis on the results and determined a list of unusual targets that you would not expect to see in the general healthy population.

During this investigation, the samples that were screened showed antibodies to 10 particular proteins that could be of potential biological interest and provide some hope that a blood test could be developed.

These exciting results are only the first piece of the jigsaw in developing a PSC blood test. Dr Rushbrook will now go on to see if these findings can be replicated in blood samples from many more people with and without PSC.