Allergy ‘On-Off’ Switch Found

Scientists working at the Virginia Commonwealth University in the United States have uncovered the possible cellular mechanism by which allergies, and other related conditions such as asthma, are regulated. Following studies in mice, they postulate that certain chemicals produced by the body may act as an ‘on-off’ switch for cells responsible for allergic responses. Furthermore, the study suggests that certain genes may prevent this switch from working properly, resulting in these immune system disorders.

Allergies are an immune system response to allergens, caused by the release of an antibody (IgE), which activates certain types of immune cells (mast cells). This induces the release of chemicals such as histamine. The release of these chemicals is what causes the recognised inflammatory responses of allergy. Whilst the role of mast cells in allergic reactions and other related conditions is well understood, research headed by John Ryan PhD uncovers the regulatory role of certain chemicals that may be lacking in individuals who suffer from allergies.

The research team, headed by John Ryan PhD, made detailed studies in mice that examined cells in the bone marrow and umbilical cord blood responsible for the production of mast cells. They found that when developing mast cells were exposed to chemicals normally used to activate these cells (cytokines IL-4 and IL-10), the developing mast cell would die. The researchers extrapolated that as both mast cells and these cytokines were produced together in the bone marrow, the cytokines could act as endogenous suppressants of mast cell maturation and survival. Hence it was suggested that these chemicals played a regulatory role. The genetic basis of this mechanism was supported by further studies of mice, that showed individuals prone to allergies and asthma had genes which affected the production of these chemicals in their bone marrow.

This research is significant as it reveals the basic mechanism that determines whether or not people will have allergies or asthma, and the severity of these symptoms. Asthma and allergies including hay fever are highly prevalent in the human population and this understanding will allow the introduction of better-targeted medications that treat the root of allergies.

         

Figure 1: Allergen bound to IgE receptor                  Figure 2: Normal allergic response process

References

Main article:

Science Daily, Cellular On And Off Switch For Allergies And Asthma Discovered (May 4, 2009); http://www.sciencedaily.com/releases/2009/04/090430101451.htm

 

Images from

http://bigteaparty.com/2008/05/01/allergies-are-the-lies-the-body-tells-itself/ and University of Minesota, http://enhs.umn.edu/current/5100/asthma/allergens.html

 

Links for more information on allergies:

American Academy of Allergy, Asthma and Immunology; http://www.aaaai.org/