Chemokine receptor expression on lung-derived T cells of mild asthmatics after segmental allergen challenge

RATIONALE: Frequent viral infections during early childhood may protect against asthma and/or allergies later in life.This protection, the socalled "hygiene hypothesis," may be related to a boost in Thl immune responses, but data to support this are lacking. METHODS:To study the influence of viral respiratory infections on immune development, umbilical cord and l-year peripheral blood samples were obtained from 284 children involved in the COAST (Childhood Origins of ASThma) Project.PHA-induced mononuclear cell cytokine response profiles were evaluated for IFN-y, IL-5, IL-10 and IL-13.Viral cultures and RT-PCR (rhinovirus) were performed on nasal lavage samples obtained during moderate and severe respiratory illnesses during the first year of life.RESULTS: There was an inverse correlation between cord blood PHAinduced IFN-y responses and the number of viral infections (r~=-0.166,p=0.005).In addition, there was a positive correlation between the number of viral respiratory infections and the change in IFN-~/during the first year (rs=0.161,p=0,007).There were no significant relationships between infection frequency and other cytokine responses, total lgE, or peripheral blood eosinophil counts at age 1 year.CONCLUSIONS: IFN-T response profiles at birth are inversely related to the frequency of symptomatic viral infections during the first year of life.In addition, these findings support one of the suppositions of the hygiene hypothesis in that infection frequency was positively associated with changes in production of the Thl cytokine IFN-y, during the first year of life.