CD40LG and cystic fibrosis: To determine whether the CF mice were more susceptible to infection, we collected longitudinal ELISA data (measuring both IgG and IgM levels) from the CF mouse colony to calculate the percentage of CF and non-CF mice that either were, or ever had been, infected with Bordetella. Over a period of approximately 2 years, we screened 180 CF mice, and 137 non-CF mice housed together.