IGHE and Alzheimer disease: We also observed a significant increase in the IgE levels in the plasma of 10-week-old NC/Nga mice maintained under conventional conditions (AD-NC/Nga mice) compared with age-matched control-NC/Nga mice, but did not find a similar significant difference between 7-week-old NC/Nga mice kept under conventional conditions and the control-NC/Nga mice (Fig. 2C).