Cortisol responses to stress in allergic children: interaction with the immune response.

Allergic manifestations are increasingly common in infants and children. Accumulating evidence suggests that the 'epidemic' increase of childhood allergy may be associated with environmental factors such as stress. Although the impact of stress on the manifestation and exacerbation of allergy has been demonstrated, the underlying mechanisms of stress-induced exacerbation are still obscure. A growing number of studies have suggested an altered hypothalamus-pituitary-adrenal (HPA) axis function to stress in allergic children. It is speculated that a dysfunctional HPA axis in response to stress may facilitate and/or consolidate immunological aberrations and thus, may increase the risk for allergic sensitization and exacerbation especially under stressful conditions. In the present review the potential impact of a hyporesponsive as well as a hyperresponsive HPA axis on the onset and chronification of childhood allergy is summarized. Moreover, potential factors that may contribute to the development of an aberrant HPA axis responsiveness in allergy are discussed.