B6.BLIMP1^+/GFP mice were treated with rapamycin 7 times over 16 days, whereupon B220⁻ BM plasma cells were sorted and applied to ELISPOT plates. (A) Mean spot sizes and (B) spot intensities were calculated as described in Methods. Dots represent values for individual mice, and horizontal lines indicate means. *P < 0.05 as determined by Student’s t test. (C) Representative images of ELISPOT wells comparing spots from control and rapamycin-treated mice. (A–C) Representative of 2 independent experiments using 5 B6.BLIMP1^+/GFP mice per group. (D) B6.BLIMP1^+/GFP mice were treated with rapamycin 7 times over 17 days, and serum IgM and IgG were quantified by ELISA. (E) Ten thousand sorted B220⁻ BM plasma cells from mice treated as in D were cultured in complete medium. After 24 hours, secreted Ig was quantified for control and rapamycin-treated cells, relative to a standard curve. *P < 0.01 as determined by Student’s t test comparing control (n = 3) and rapamycin-treated (n = 4) samples. (F) Control and rapamycin-treated mice (treated as in D) were stained for intracellular kappa light chain (IgKappa) by flow cytometry. Shown are representative histograms for control (n = 3) and treated (n = 4) mice. (D–F) Representative of 2 independent experiments. (G) C56BL/6 mice were immunized with NP-CγG, and the serum anti-NP IgG1 response was monitored over time. During the indicated time period (gray region), one cohort of mice was treated twice weekly with rapamycin. *P < 0.01 as determined by Student’s t test comparing control (n = 5) and rapamycin-treated (n = 5) samples. (H) NZB/W mice were monitored over time for serum anti-dsDNA IgG antibodies. One cohort of mice was treated twice weekly with rapamycin beginning at 30 weeks of age and ending at 34 weeks (gray region). *P < 0.01 as determined by Student’s t test comparing control (n = 10) and rapamycin-treated (n = 10) samples.