Scientists have found that children who kept cats as pets had developed a better immune system against asthma.
Scientists have found that children who kept cats as pets had developed a better immune system against asthma.
This finding was originally thought to suppport the "hygiene"or "cleanliness" hypothesis. According to this, a lack of early exposure to bacteria or allergens keeps one branch of our immune system, mediated by "Th1" from developing properly.As a result, the immune system gets out of balance and the other branch, mediated by "Th2" cells over reacts causing runny nose, sneezing and wheezing of allergic reactions. Supporters of cleanliness hypothesis reasoned that exposure to cats might be protecting from asthma by strengthening the Th1 system.
To prove this Thomas Platts-Mills and his colleagues from the University of Virginia looked at the immune reactions of 226 children to cat allergens in their hormones. They found that 1 in 5 of the children showed an immune response to cat dandruff without having any allergic reaction. These children's immune system produced an antibody called IgG4 rather than IgE which causes allergies. Both antibodies are part of the Th2 system. Researchers believe that IgG4 suppresses the harmful IgE response.
The children with raised IgG4 clearly aren't getting their protection from stimulated Th1 system, instead the protection is from a modified version of the Th2 response--without the risk of asthma or other allergic reactions.
