Stop hating your belly fat! Some of it may save your life.

In a paper appearing Wednesday in the journal PLOS ONE, Loyola University Chicago researchers found that a particular kind of belly fat is involved in regulating the immune system, opening the door for new kinds of drugs for autoimmune diseases like Crohn's and lupus.

The flab in question is a sheet-like tissue called the omentum that lines the abdominal cavity. Though parts of the omentum have been used to promote healing in injured tissues for more than a century, the mechanism by which it works has not been well understood, researchers said.

But we now have evidence that the omentum is not just fat sitting in the belly, senior author Makio Iwashima said in a statement Wednesday.

Iwashima and his team tested the effects of mouse omentum cells by growing them in the same medium with mouse T cells -- the front- line troops of the immune system -- and antibodies. Normally these T-cells would have been activated by the presence of the antibodies and proliferated, but in this case the T-cells died instead. The omentum cells did not, however, kill inactive T-cells.

At first blush, killing immune cells doesn't sound like a good idea. But without proper controls, an overactive immune system can damage the body when it begins attacking normal tissue, as seen in autoimmune disorders like lupus.

The researchers think omentum cells emit some kind of molecular signal that tamps down the immune system. If that signal is isolated, it could form a basis for a new class of immunosuppressant drugs for autoimmune disease patients and people with organ transplants, who need to rein in their immune systems in order to prevent their bodies from rejecting donor organs.

Iwashima and his team also found that the omentum is full of mesenchymal stem cells, which can differentiate into many different cell types, suggesting that the membrane plays a key role in tissue regeneration and repair for damaged organs.

SOURCE: Shah et al. Cellular basis of tissue regeneration by omentum. PLoS ONE 7(6): e38368.