IMMUNE cells taken from humans could soon replace animals in tests to
identify chemicals that cause skin allergy.
Today, allergy testing is done in mice using the 鈥渓ocal lymph node assay鈥�.
Analysts apply a chemical to the ears of mice, then extract a nearby lymph node.
If white blood cells from the node are dividing quickly, it means the chemical
is an allergen. 鈥淭he holy grail is to find a way of doing this without animals,鈥�
says Ian Kimber of AstraZeneca鈥檚 toxicology lab at Macclesfield, Cheshire.
Allergens landing on the skin are carried down to a lymph node by specialised
Langerhans cells, which bump up their output of interleukin-1-beta, a signalling
molecule that causes inflammation. Kimber wondered if the upsurge in
interleukin-1-beta could be used to detect antigenic chemicals. Langerhans cells
are hard to isolate, so Kimber and his team cultured dendritic cells in a
special way to create cells resembling Langerhans cells.
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These pseudo-Langerhans cells pumped out more interleukin-1-beta when exposed
to allergens, enough to screen out the 鈥渂ad boys鈥�, but not enough to reveal mild
reactions. Kimber is confident that he can make his test more sensitive by
focusing on the expression of other genes that respond more strongly to
antigens.