Scientists at the Franz-Volhard Clinic for Cardiovascular diseases and the Max-Delbrück-Centre for Molecular Medicine, both in Germany, discovered that a specific protein called NB1 (or CD177) helps anchor an autoantigen to the surface of white blood cells, which is itself recognised, and bound, by the immune system. The subsequently activated cell then attacks the body's own blood vessels, causing inflammation.

Autoimmune vasculitis is the name given to a broad range of potentially life-threatening conditions that can occur in any and all organs of the body. Currently, the condition is treated with drugs designed to suppress the entire immune system. However, this leaves the patient open to other infections.

For example, one form of vasculitis called Wegener's granulomatosis requires immune therapy and dialysis. However, even if the treatment is successful and the patient comes off dialysis, there is always a risk it may reoccur. However, drug developers could now design a NB1 inhibitor, which could potentially cure the disease and avoid recurrances.

"That is why our findings provide hope for patients with vasculitis," said Professor Ralph Kettritz.

"A specific therapy approach based on our study may hold the key to overcoming the disease."

The inflammation seen in vasculitis is specifically caused by autoantibodies called antineutrophil cytoplasmic autoantibodies (ANCAs) - so called because the white blood cells they activate are called neutrophil granulocytes.

It has been established previously that ANCA attacks cells which present a specific antigen on their surface - proteinase 3 (PR3). However, although PR3 is found inside all neutrophil cells in the cytoplasm, only a few show the enzyme on their surface.

So, the researchers set out to discover how PR3 comes to be physically displayed on the outside of the neutrophil cell. The team examined neutrophils from three different sources: from healthy volunteers; from patients with vasculitis; and cells differentiated from stem cells.

Most importantly, they found that only cells with high levels of NB1 had PR3 on their surface. The direct relationship between the two was confirmed in two ways. First, the scientists reduced the amount of NB1 on cell surfaces and saw a corresponding decrease in PR3 levels, and secondly, infecting other cells with NB1 resulted in PR3 surface binding across all cell types.

However, writing in today's issue of the journal Blood, the researchers said the work also raises a number of questions. For example, although exogenous PR3 binds to NB1 on the surface of cells, in addition, it could also be possible that the two bind together inside the cell before moving to the surface or that they translocate to the surface independently before binding together.