Endotoxin, a toxic substance made by certain types of bacteria, may reduce the risk of developing the allergic skin condition eczema or wheezing in children if they are exposed to it up to age 3, suggests a study presented at the American Thoracic Society 2007 International Conference, on Sunday, May 20.

Endotoxin is a part of the cell wall of gram-negative bacteria, a type of bacteria that often causes disease. Endotoxin is released when the bacteria dies or is damaged. The new study found that the lower the amount of endotoxin in young children's homes, the more likely they were to have wheezing or eczema by age 3. The higher the amount of endotoxin in their homes, the less likely they were to develop either condition by age 3.

"We're trying to find why children exposed to endoxotin have lower levels of disease early in life," says researcher Melisa Celaya, M.A., of the Arizona Respiratory Center in Tucson.

Celaya found that certain environmental factors increased the levels of endotoxin in a home: having a home older than 30 years, substandard home conditions, carpeting, a musty smell and interior wall leaks were all associated with higher levels of endotoxin.

Blood samples were taken from 484 children enrolled in the Infant Immune Study at different ages, up to 5 years of age. "We will be looking at the relationship between endotoxin levels in the home and chemicals (called cytokines) that are produced by certain immune system cells, to see why children exposed to lower levels are developing more allergic symptoms later on," she says. "This study is unusual in that we are following children over a long period, and are looking at both environmental factors and immunological factors, so we can correlate the two."

The researchers also plan to study whether genetic predisposition changes a child's responses to environmental triggers.

"Predictors of House Dust Endotoxin Levels and Relation with Later Wheeze and Eczema in Early Life"(Session A105; Abstract # 5165; Poster Board # 914)

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