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Journalism of Courage
A new study has found that a part of the body’s immune system, thought to exacerbate potentially lethal reactions to snake bites and insect stings, actually helps break down the animals’ venom as well, revealing proteins that could one day help medicate bites. Long pilloried as the cause of allergic reactions, the immune system’s mast cells release a number of proteins and other chemicals, including those that inflame the skin after a bite or sting, causing swelling, soreness and itching.
Scientists previously thought mast cells, a part of the immune system that can be triggered by many stimuli and not just allergic reactions, were activated by venom to release proteins and other chemicals that harm tissues.
‘‘It was actually the opposite,’’ said Stephen Galli, a professor of pathology at Stanford and the study’s senior researcher. The new research has found the cells’ positive effects outweigh the negative because they release enzymes that break down the toxins in venom.
The research measured the effects of venom from an Israeli mole viper, as well as honeybees and two poisonous snakes common in North America, on mice with and without mast cells, according to the study written by Martin Metz and published on Friday in the journal Science. The mice with mast cells were able to withstand 10 times the amount of venom.
One day, if scientists find a way to safely use the enzymes that can break down venom, the research may lead to new antivenin compounds that could be used to treat bites. ‘‘That’s a big jump from what we’ve done,’’ Galli said, ‘‘but we hope that our findings will encourage people to try to do it.’’
Previous mast-cell research has concentrated on their negative effects, said Juan Rivera, who studies the cells at the National Institutes of Health. ‘‘I think we haven’t understood the roles of mast cells in physiology,’’ Rivera said, ‘‘and it could turn out that these cells have an incredible role in protecting us against many harmful agents.’’
Galli said the team used only a ‘‘pinch’’ of venom for the entire study—though he had to bring it back from Israel himself. He was required to hold a special permit from the US government and write ‘‘Israeli mole viper venom’’ on his declaration form. The study could also prompt new research into the roles of mast cells. ‘‘It’s an interesting cell,’’ Rivera said, chuckling, ‘‘though I’m biased because I work with them.’’ (T W Farnham)
