New Immune System Signals Discovered

Credit: ZEISS Microscopy

In a groundbreaking discovery to rewrite the textbooks, a type of immune signal that was once considered rare may actually constitute a third of all signals

When particular immune cells run into a foreign body or protein, that gobble it up and break it down - displaying fragments of these 'antigens' on their cell surface. These act as signals for other cells and mobilise the immune system accordingly. Previously it was believed that this was done in a fairly orderly manner, with the fragments being displayed separately and in sequence. New research published in Science has uncovered that in fact around 30-40% of these fragment epitopes may be formed by splicing together different elements to form new ones altogether. 

"It’s as if a geographer would tell you they had discovered a new continent, or an astronomer would say they had found a new planet in the solar system. And just as with those discoveries, we have a lot of exploring to do"

An increased complexity

The epitope creation process

Courtesy of an improved methodology, a team of researchers were able to map the cell surface in more detail than before. In doing this they stumbled across a surprisingly abundance of spliced epitopes which were believed to be extremely rare. Spliced epitopes are created following proteasomal breakdown of a foreign protein (the proteasome is a specialised area of the cell responsible for breaking down proteins). Fragments from different parts of the protein are meshed together to form a blended epitope, which provides a larger spectrum of signals for the immune system to recognise. This improves disease detection ability, but the researchers also speculate it contributes to immune disorders too, as certain spliced epitopes may accidentally resemble host proteins - signalling to other cells to destroy healthy cells and leading to potential autoimmune disorders. 

"The discovery of the importance of spliced peptides could present pros and cons when researching the immune system. For example, the discovery could influence new immunotherapies and vaccines by providing new target epitopes for boosting the immune system, but it also means we need to screen for many more epitopes when designing personalised medicine approaches”

Read more at Imperial College News