Respiratory allergy in agricultural workers: recent developments.
OBJECTIVE
To review recent evidence on the relationship between occupational exposure to allergens and asthmagens, and risk for developing allergy and asthma and the role of modifying factors in farmers and farm workers.


RESULTS
Recent studies identified agents that have not been associated with allergy or asthma in farming populations before. The most intriguing findings, however, are those that suggest that the development of atopy and asthma might be influenced by exposure to pathogen associated molecular patterns (PAMPs), including endotoxin.


CONCLUSIONS
The adverse and potentially protective effects of microbial exposures in the farm environment are discussed. Recent findings indicate that it is very likely that the protective effect of exposure to PAMPs such as endotoxin is not limited to childhood age. The protective effects that probably developed during childhood can still be observed at adult age. Furthermore, it even seems likely that exposures at adult age (in occupational environments), which stimulate the innate immune system, have an effect on allergy, independently of childhood exposure. It is hypothesized that reversal of atopy might occur as a result of high exposure to endotoxins and other PAMPs.
Heederik
Dick
D
Institute for Risk Assessment Sciences, Division of Environmental and Occupational Health, IRAS, University Utrecht, Utrecht, The Netherlands. d.heederik@iras.uu.nl
Sigsgaard
Torben
T
D000382:Agricultural Workers' Diseases / Q000276:immunology*; D000485:Allergens / Q000009:adverse effects*; D015984:Causality; D004731:Endotoxins / Q000276:immunology*; D006801:Humans; D016273:Occupational Exposure / Q000009:adverse effects; D012130:Respiratory Hypersensitivity / Q000276:immunology*; D018417:Th1 Cells / Q000276:immunology; D018418:Th2 Cells / Q000276:immunology
D000485:Allergens; D004731:Endotoxins