Scientists say they have discovered precisely how a cell involved in allergy is made, which may help with finding new preventive treatments.
The researchers hope their finding will help with finding new treatments
Two papers in Nature Immunology describe how one type of a family of immune cells, called T helper cells, develops and cause disease.
The CD4 T cell originates from cells unique to its close cousins and makes a molecule called interleukin 17 (IL-17).
IL-17 triggers allergy and is important in diseases like asthma and arthritis.
Scientists hope that it might be possible to develop treatments to block this newly identified process to treat the symptoms of allergy and autoimmunity - where the body attacks itself.
Both US teams, from the University of Alabama at Birmingham and the University of Texas, studied what was happening in the immune system of mice.
Past research has already shown that mice deficient in IL-17 are less able to fight off bacterial infections because they lack certain factors needed to mount an attack, particularly in the lung.
But when there is too much of this molecule the inflammatory response can be too much and cause problems.
IL-17 has been associated with many inflammatory diseases in humans, including rheumatoid arthritis, asthma and organ rejection.
The US researchers found IL-17 was produced by a distinct type of CD4 T cell in the mice that they called TH-17.
This newly identified lineage of cell is prompted to develop by different signals than other CD4 T cells, which had not been explained until now, said the researchers.
They said: "Further research on this subset of TH cells should demonstrate greater complexity of TH regulation and function in immune responses.
"Additional research may also show that modulation of IL-17-producing T cells therapeutically is an important method for treating T-cell mediated chronic inflammatory diseases."
Dr Madeleine Devey of the Arthritis Research Campaign said: "These studies are very interesting and add to the understanding of the hugely complex process of inflammation.
"IL-17 is yet another proinflammatory cytokine that we know is expressed in the joints in rheumatoid arthritis.
"Understanding how the T cells that produce IL-17 develop and are regulated will provide further possibilities for the development of specific therapies that will interfere or prevent the inflammatory processes in diseases like rheumatoid arthritis."
Dr Lyn Smurthwaite, Asthma UK's research development manager, said: "Inflammation and asthma are closely linked, and by understanding how inflammation occurs we can gain insight into how asthma develops.
"We look forward to seeing these results translated into the human immune system, especially with respect to their potential relevance to the development of asthma."