Environment and T regulatory cells in allergy.
The central role of T regulatory cells in the responses against harmless environmental antigens has been confirmed by many studies. Impaired T regulatory cell function is implicated in many pathological conditions, particularly allergic diseases. The "hygiene hypothesis" suggests that infections and infestations may play a protective role for allergy, whereas environmental pollutants favor the development of allergic diseases. Developing countries suffer from a variety of infections and are also facing an increasing diffusion of environmental pollutants. In these countries allergies increase in relation to the spreading use of xenobiotics (pesticides, herbicides, pollution, etc.) with a rate similar to those of developed countries, overcoming the protective effects of infections. We review here the main mechanisms of non-self tolerance, with particular regard to relations between T regulatory cell activity, infections and infestations such as helminthiasis, and exposure to environmental xenobiotics with relevant diffusion in developing countries.
Braga
M
M
Allergy Unit, Spedali Civili, Piazzale Spedali Civili, 25123 Brescia, Italy. marinaetbraga@hotmail.com
Schiavone
C
C
Di Gioacchino
G
G
De Angelis
I
I
Cavallucci
E
E
Lazzarin
F
F
Petrarca
C
C
Di Gioacchino
M
M
D003141:Communicable Diseases / Q000276:immunology*; D004781:Environmental Exposure; D004785:Environmental Pollutants / Q000276:immunology*; D006801:Humans; D006967:Hypersensitivity / Q000209:etiology / Q000276:immunology*; D050378:T-Lymphocytes, Regulatory / Q000276:immunology*; D015262:Xenobiotics / Q000276:immunology* / Q000633:toxicity
D004785:Environmental Pollutants; D015262:Xenobiotics