Pollen which is allergenic releases much greater amounts of nitric oxide and nitrite than a non-allergenic pollen

Hayfever is a major irritation for up to 20% of the population in most economically developed countries.

Pollen is the cause of this allergic reaction but what causes it and why?

Dr Jo Bright and Dr John Hancock of the University of the West of England have found evidence that nitric oxide (NO) and nitrite is released by pollen grains, and they suggest that this could be what triggers the allergic response in the nose. Their research was presented at the Society for Experimental Biology's Annual Main Meeting in Glasgow on Tuesday 3 April.

Dr Bright says, "Our research is the first to show that pollen which is allergenic releases much greater amounts of NO and nitrite than a non-allergenic pollen."

Dr John Hancock says, "The discovery of the potential link to hayfever was made almost by accident. Whilst working on a separate project on plant reproduction we found that pollen was producing NO as a by-product. We realised that this might have implications for the allergic response many people have to pollen. This current study has enabled us to look closely at how the plant produces NO, but we need to carry out further research so we can prove the link between the NO and the allergic reaction. These findings are very exciting and I believe they could have implications for how we treat hayfever in the future, but there is still a lot of work to do before we can fully establish the link and we are now looking for funding so we can carry on this research."

Previous research indicates that the male parts of the plant (the pollen) may produce NO as a signal to the female parts (the stigma) during reproductive processes. NO and nitrite signalling are also important mechanisms in mammals and Dr Bright and her colleagues intend to investigate what role the pollen-derived NO and nitrite plays in human cell inflammation and irritation during hayfever.