Weak immune response blamed

In the long-running debate over whether Crohn's is caused by over-active or under-active immune systems the New Scientist reports on research that tips it in favour of the under-active hypothesis.

Segal and his colleagues got their first clue when they noticed a weaker immune response in people with Crohn's than in healthy people after both groups were injected with heat-killed Escherichia coli. The team reasoned that this lukewarm response might allow an infection to build up and eventually trigger a debilitating secondary immune response, resulting in Crohn's.

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The team concluded that ineffectual rallying of immune cells in people with defective macrophages is what allows intestinal bacteria to run amok in the early stages of an infection, setting in motion the series of events that leads to Crohn's disease.

The full research published in the The Journal of Experimental Medicine contains the juicy details in addition to good background information on the current status of Crohn's research. Although they don't specifically mention new treatments resulting from this discovery, it seems likely to open new avenues for scientists to explore.