Blood cells ‘gas’ bacteria

Poisonous gas was used as a destructive weapon in World War 1, but when it comes to the human body and fighting invading bacteria, it appears that gas might be a key factor in how we control infection.

University of Otago Christchurch scientists in New Zealand, Professor Tony Kettle and PhD candidate Melanie Coker, have recently added another crucial piece to the jigsaw puzzle of how our body defends us against bacterial infection, but which paradoxically often causes other inflammatory problems.

For the first time ever Kettle and Coker have discovered that a part of this bacteria killing process may involve gassing the invading bacteria within the white blood cell itself, after bacteria have been enveloped and ‘eaten’ by scavenging neutrophils .

It’s a unique discovery which has just featured in two overseas publications Chemical and Engineering News and the American journal, Chemical Research in Toxicology, where it is featured as a cover story.

The scientists have shown that the interaction between proteins and hypochlorous acid (household bleach) in white blood cells, results in the production of toxic chloramine gas, which has a lethal effect on any bacteria. Although this finding has not been proven within living cells it has been replicated in the laboratory using proteins from human cells and hypochlorous acid.

Over recent years researchers at the University of Otago, Christchurch have been slowly drilling down into our understanding of how we fight infections. What exactly are the precise mechanisms and chemical reactions which go on in that partly understood basic unit of the body, the human cell?

This latest research from the Free Radical Research Group significantly advances previous findings which demonstrated that our bacteria-fighting foot soldiers, or white blood cells, actually use the equivalent of chlorine bleach to kill invading bacteria.

The white blood cells, or neutrophils, surround and consume potentially damaging bacteria, and deliver the final ‘coup de grace’ through the actions of bleach. Now the researchers have discovered that the body’s arsenal is even more effective, and has another powerful weapon in its fight against bacterial infections, chloramine gas.

Why is this important? One of the key reasons is that for some time it’s been known that the action of white blood cells, when they attack bacteria, can cause inflammation that destroys healthy body tissue in chronic diseases like rheumatoid arthritis or cystic fibrosis; and even promote certain cancers.

Now that chloramine gas has been identified as a likely player in this process, new approaches can be developed to control inflammatory response in numerous diseases.

This research was funded by the Health Research Council of New Zealand and supported by the Centre of Research Excellence for Growth and Development.

(Source: Chemical Research in Toxicology: University of Otago: December 2008)