A research team at the Helmholtz Center for Environmental Research (UFZ) led by Drs. Irina Lehmann and Kristin Weiβe has found evidence for a link between a particular stem cell population and environmental toxins. These results could have significant implications for allergy sufferers.
All the blood cells are made by hematopoietic stem cells in the bone marrow. These bone marrow stem cells divide to renew themselves and generate progenitor cells that can divide a little and differentiate into specific types of blood cells. The progenitor cells spend some time in the bone marrow, but are released into the peripheral bloodstream to replenish lost blood cells.
One particular progenitor cell is called the eosinophil/basophil progenitor, and this multipotent stem cells can either differentiate into an eosinophil or a basophil. Eosinophils help fight parasite infections, but they also play an important role in allergies. Basophils can fight infections, but they also become stationary in tissue and are known as mast cells where they can release chemicals that cause allergies in response to allergen, which are substances that cause allergies.
Several previous studies have shown that allergy sufferers, be they children or adults, have higher levels of eosinophil/basophil progenitor cells circulating in their blood, and that those individuals whose umbilical blood has higher levels of circulating eosinophil/basophil progenitor cells are at higher risk for allergies later in life.
The UFZ team wanted to clarify the relationship between allergies and the presence of eosinophil/basophil progenitor cells. Since environmental toxins are known to stimulate allergies in younger people, they hypothesized that environmental toxins might increase the quantity of circulating eosinophil/basophil progenitor cells in young children.
Lehmann and Weiβe examined blood samples from 60 one-year old children and used skin tests to measure the tendency of these children to form rashes after exposure to allergens (substances that cause allergies). The skin tests are a measure of the sensitivity of the children to allergies. They also measured the levels of environmental toxins to which the children’s families were exposed.
The results from this study were remarkable. Children whose families were exposed to higher levels of volatile organic compounds or VOCs, which are quite prevalent in cigarette smoke, showed higher levels of circulating eosinophil/basophil progenitor cells and were more sensitive to allergens. Thus the environmental influences seemed to influence the levels of those stem cells known to sensitize people to allergies.
Lehmann noted: “That VOCs, large amounts of which are released with cigarette smoke, have the greatest effect on stem cells was not entirely unexpected.”
Adding to this, Weiβe said: “Just as important, however, is that we can show that alterations in the number of stem cells as a result of harmful substances that place only in children who have been afflicted with skin manifestations.” Thus there is a direct relationship between someone’s genetic predisposition for a disease and the environmental influences to which they are exposed. Another way to say this would be that there are environmental and lifestyle factors which determine whether a genetic predisposition to have allergies results in actually suffering from allergies. The environmental effects influence the levels of a circulating stem cell known to play a role in allergies.