Children at risk for asthma: home allergen levels, lymphocyte proliferation, and wheeze. 
Allergic asthma is a common childhood disease.  Although T-lymphocyte activation plays a critical role in allergic asthma, the environmental factors promoting lymphocyte activation in children are not well defined.  In a cohort of children at risk for asthma (n = 114), we determined whether the levels of cockroach (Bla g 1 or 2), house dust mite (Der f 1), and cat allergen (Fel d 1) in the home during infancy was associated with subsequent allergen-specific lymphocyte proliferation in later life.  Dust samples from multiple sites in the home were collected at 3 months of age and were measured for allergen levels.  Serial questionnaires were applied.  At a median age of 2 years, PBMCs were isolated and lymphocyte proliferation to the home allergens and PHA was determined.  Increased lymphocyte proliferative responses to Bla g 2 were associated with higher home levels of Bla g 1 or 2 (P for trend with kitchen Bla g levels =.011), in analyses adjusting for cold in the past week.  Proliferative responses to Der f 1 were higher in homes with family room levels of Der f 1 > or =10 microg/g dust than in homes with Der f 1 <2 microg/g, but differences were not significant in analyses adjusting for cold (P =.  15).  Repeated wheeze in the first 2 years of life was associated with increased allergen-specific and PHA proliferative responses.  Early-life cockroach allergen exposure at 3 months of age predicts allergen-specific lymphocyte proliferative responses at a median of 2 years of age.