Sex-related differences in immune development and the expression of atopy in early childhood.

Background: Sex and age are known to influence the clinical expression of asthma and allergic diseases.

Objective: We sought to evaluate whether immune response profiles also vary by sex and age.

Methods: We performed a prospective birth cohort study (Childhood Origins of Asthma) designed to evaluate interactions among age, sex, immune responses, and virus infections on the development of asthma and allergic diseases.