You may have ignored the symtoms as flu or common cold but a child we frequently sneezes or coughs a lot, often develops rash or hives and gets stomach stomach ache may be allergic to certain foods.If left untreated, allergies can lead to a potentially lethal anaphylactic shock - a life threatening allergic reaction. According to a new study, the good news is that many children outgrow their allergies, presumably as the immune system learns to tolerate foods initially mistaken as "foreign". The research was conducted at the La Jolla Institute for Allergy and Immunology (LJI) in US.Researchers suggest that children who have more limited exposure to novel foods than adults, are more susceptible to food allergies. "The immune system evolved to protect us from things that are not ourselves, like viruses or pathogens, yet we consume nutrients, which are themselves foreign," said a researcher Charles Surh from La Jolla Institute for Allergy and Immunology (LJI) in the US."Our work shows food tolerance is acquired and involves specific populations of T cells that develop following its consumption. Without them, we would mount a strong immune response to macromolecules contained in food," Surh added.This is one of the first studies to demonstrate that consumption of a normal diet stimulates cells in the gut that suppress rejection of food by the immune system. The research was published online in issue of Science and it explains how food tolerance emerges over time in normal individuals.Like pathogens, food displays macromolecular markers known as antigens that announce to the immune system that food is "foreign". For the study, researchers conducted "antigen-free" mouse models, these animals were not only raised in a germ-free environment. Antigen-free mice were depleted of Tregs in the small intestine whereas a large number of these Tregs were present in germ-free counterparts, the study found. Interestingly, germ-free mice are known to be highly susceptible to allergies.The team explained that proteins contained in food stimulate the development of Treg cells. It also hints at the fact that Tregs present in the gut of normal mice might suppress a potentially disastrous immune response to those proteins. Hence, the presence of both food-and microbe-induced populations of Tregs is required to prevent allergic symptoms. In simple terms, consumption of a normal diet stimulates cells in the gut that suppress rejection of food by the immune system which is why some children are more prone to develop allergies. This study explains what happens on a cellular basis as some children outgrow it - they may be expanding their repertoire of Tregs that recognise new foods as 'safe'.With inputs from IANS
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