The human immune system has evolved to have appropriate defensive response to various dangerous pathogens while ignoring innocent ones such as helminths. The constant presence of helminth infections is still prevalent in developing countries and it is largely controlled in the developed or western world. It has been proposed that knowledge of the immune system by certain microbes and parasites can prevent in part the development of inflammatory disease.
In particular, the interplay between helminth infection and allergy disorders have been studied in great detail. It has been suggested by Smits et al., in 2010 that helminth-induced mechanisms not only regulate host immunity to the worms, resulting in mutually beneficial environment for survival of both parasite and host, but may also control the development of allergic disease.
Both allergy and helminth infection are linked with raised levels of igE, tissue eosinophilia and mastocytosis and CD4+ cells that preferentially secrete Th2 cytokines; IL-4, 5 and 13. It is suggested that increased an increased level of IgE in asthma in some cases may be due to a faulty IL-4 gene receptor producing mass amounts of IgE and an increase in IgE in helminth may be due to the worm inducing a Th2 response.
Mast cells play a big role in both asthma and helminths and this is due to both the conditions causing a dominant Th2 response. As mentioned earlier, both conditions witness a dramatic increase in levels of IgE which is what causes degranulation of the mast cells releasing many products and cytokines which have their effect in both asthma and helminth.