Fat-fragments could help our immune system treat diseases such as rheumatoid arthritis, Type 1 diabetes and some types of cancer.

A team of scientists at Monash University have captured how another arm of our immune system protects us against infection, with a little help from a marine sponge. The information has implications for the development of therapies for prevalent diseases like rheumatoid arthritis, Type 1 diabetes and some types of cancer.

Dr Natalie Borg from Monash University and colleagues in the collaboration used synchrotron radiation to visualise how NKT cells in our immune system recognise fat-fragments that have been captured by another immune system molecule called CD1d. The research findings were published in the international science journal 'Nature'.

CD1d is an immune system molecule that captures fat-fragments in our body. The fat-fragments are captured for surveillance by other cells in our immune system called NKT cells. NKT cells survey the captured fat-fragment and determine if the fragment is 'familiar' or 'unfamiliar' to our body. An 'unfamiliar' fat-fragment may be a marker of a bacterial infection. An NKT cell must recognise this and send a 'signal' to our immune system to mount a specific immune response.

Dr Borg said we have previously had a firm grasp on how our immune system recognises protein markers of infection from viruses or bacteria, but had a limited understanding of how fat-fragments are recognised by NKT cells. Now we know that the mode of recognition is quite different when compared to protein.

"Not only is this event crucial to our defence against bacterial infection, but it also has more significant wider implications. A broad range of disease states such as atherosclerosis, autoimmune disease and allergy are associated with an imbalance in the 'signal' that NKT cells send" Dr Borg said.

"By understanding what factors influence the NKT cell 'signal' that is sent, we can learn to manipulate the system to give us a more desired immune response to help combat a particular disease."

"The fat-fragments themselves can be used to manipulate the system. In fact, the fat-fragment we've captured in our study has potent anti-cancer activity in mice and funnily enough it comes from a marine sponge," said Dr Borg.