 - There is a unique pattern of immune development that is driven by specific urban exposures in early life, and this pattern of immune development is characterized by: 1 impairment of antiviral responses and 2 accentuation of Th2-like responses e.g. cockroach-specific Interleukin-13IL-13. The clinical effects of these changes in immune development are frequent virus-induced wheezing and allergic sensitization by 3-4 years of age, and these characteristics synergistically increase the risk of asthma at age 7 years. 