FAIM is elevated in GCB. A, Mice were immunized with TNP-KLH in alum. At 10–14 days after immunization, GCB and FOB were sort-purified as described in Materials and Methods. FOB were >99% pure and GCB were >94% pure upon postsort reanalysis. B, From sorted GCB and FOB, RNA was prepared, reverse transcribed, and evaluated for expression of Aid, and of Faim by real-time PCR. Expression levels were normalized to β2-microglobulin. Mean values for five independent experiments are shown, along with lines corresponding to the SEM. C, From sorted GCB and FOB, lysates were prepared and evaluated for expression of FAIM by Western blotting. Blots were stripped and reprobed for actin content as a loading control. One of two comparable experiments is shown.