Our immune system’s ‘teachers’ are still full of surprises

These cells are found in any body tissue, and especially those regularly exposed to the outside world – the skin, airways and, via our food, the gut. They can reach between and around other cells to form an immune ‘filter’. “Dendritic cells can initiate or turn off immune responses. Fundamentally, their job is to educate our immune system on what to react to and what to ignore” explained Prof Franca Ronchese, leader of our Immune Cell Biology programme.

Prof Ronchese has been studying dendritic cells for several years, to understand – at a cellular and molecular level –how they respond to environmental changes, in order to trigger allergies. “Even today, we don’t understand the causes of allergic responses, just their symptoms” says Prof Ronchese. In the team’s latest paper, published in the prestigious Journal of Experimental Medicine, they explored the response of dendritic cells to two allergens – one from a parasite called Nippostrongylus brasiliensis, and dibutyl-phthalate, a chemical plasticizer implicated in allergies in children.

Key to this research project’s success was the use of “omics”, or ‘big data’. To understand how dendritic cells respond to allergens, the team identified and compared every molecule produced by healthy and “allergic” dendritic cells, creating a list of hundreds of changes. “Handling this vast amount of data is a challenge in itself, requiring the use of biostatistics and largecomputers, to store, process and visualise the data,” explained Prof Ronchese.

Their surprising results showed that while the overall immune responses to both the chemical and the parasite allergen were similar, the mechanism behind it was very different. “This is the first time such a study has been carried out,” Prof Ronchese said. “We expected to see more similarities than differences, but that was not the case. This is an initial step on a complex scientific path. There is still a lot to discover and understand about allergies!”

Reference: L.M. Connor et al, “Th2 responses are primed by skin dendritic cells with distinct transcriptional profiles.” J. Exp. Med. 2017, Vol. 214 (3). https://doi.org/10.1084/jem.20160470