Memory B cells are specifically affected by vitamin D3 restriction. Splenocytes were analyzed for populations of (D) total B220+ B cells, (A–C) transitional B cells—T1 (B220+AA4.1+IgM+CD23-), T2 B220+AA4.1+IgM+CD23+), and T3 (B220+AA4.1+IgM-CD23+), (E) germinal center B cells (B220+IgM-GL7+CD38low), (F) memory B cells (B220+IgM-CD38hiGL7-), (G) plasmablasts (B220-CD138+IgM+) and (H) plasma cells (B220-CD138+IgM-). (I) Serum IL-10 levels. Each symbol represents an individual mouse, and the mean of each group is represented by a horizontal line. * p < 0.05, ** p < 0.01; unpaired t-test with Welch’s correction. GC = germinal center.