Number and frequency of (A) mature activated, (B) naïve, (C) class-switched, (D) and immature B cells in the lymph node harvested from SPF (black) and NME (green) offspring at 2, 3, or 6 weeks of age. (E) Lymph node B cell composition. (F) Number and frequency of plasma cells in the lymph node. 10-15 mice/group/time point. Data were collected from three individual experiments per group per age over two years. Example flow plots are from a 6-week-old NME mouse. (G) Total IgG concentration (ng/mL) in the plasma of 3-week-old SPF and NME mice measured by a single ELISA, samples were assayed in duplicate. 3-4 mice/group. *p ≤ 0.05, **p ≤ 0.01, ***p ≤ 0.001, ****p ≤ 0.0001.