Tracking down allergenic substances

At present, animal tests are the only way of determining whether a particular chemical can cause an allergic reaction.

Researchers working on the Sens-it-iv project are developing alternative methods that can reliably predict the allergy risk of chemicals – without animal testing.

There is danger lurking everywhere – in textiles, cosmetics, medicines, detergents, foodstuffs, toys, and even at work. Potentially allergenic substances surround us all the time. The dramatic increase in allergy-related diseases makes it increasingly important to take preventive action. Two years ago, the EU issued a new directive requiring all chemicals to be reassessed with respect to toxic risk. One very important question is “Which substances can lead to sensitization and from there to the development of allergies?”

In the past, tests had to be performed on animals in order to answer such questions. Scientists at the Fraunhofer Institute for Toxicology and Experimental Medicine ITEM in Hannover are currently engaged in work for the EU Sens-it-iv project to develop alternative methods that will one day eliminate the need for animal testing. “We have focused our attention on substances that are absorbed by the body via the lungs, i.e. by inhalation,” says project manager Dr. Armin Braun. “We do not administer chemical substances to live animals to test for allergy risk; instead we use specimens of lung tissue.” This tissue is generally obtained from rodents, and cut into very fine slices using a special, highly precise method. The chemical being tested is applied to these so-called precision-cut lung slices (PCLS) and the scientists then use various methods to evaluate the tissue’s reaction. This includes identifying which genes might be expressed in the tissue, or determining which protein molecules are produced in greater abundance by the cells. Are any of them implicated in the immune response process, i.e. are they likely to trigger an allergic reaction? By examining the tissue under a microscope, it is possible to observe potential interactions between the cells and the immune system. Because the PCLS method is based on whole sections of tissue, the researchers can observe physiological processes in natural cell aggregates, almost exactly as they would occur during an immune response in the body.

At present, the scientists are using chemical substances already known to provoke an allergic reaction, as a means of refining the PCLS method. But they soon intend to start testing many other substances that have not been evaluated before. These in-vitro tests performed in a culture vessel require far fewer animals – merely enough to harvest the lung tissue. The main beneficiaries of Sens-it-iv will be industry – cosmetics, textiles, pharmaceuticals – and public authorities in charge of monitoring occupational health and safety.