On the Cover: Immunohistochemical staining for B lymphocyte-induced maturation protein-1 (Blimp-1) in hu- man tonsils. Serial sections were stained for Blimp-1 (red) and a mixture of CD10, CD138, CD23 (blue) (A), or Blimp-1 (red) and CD20 (blue) (B). Tonsillar epithelial regions are boxed (upper panels) and enlarged in the lower panels; epithelial cells are detected by strong Blimp-1⁺ staining. Boxed regions show clusters of CD10^-CD138^-CD23^-CD20⁺ memory cells that are Blimp-1^- as well as CD138⁺CD20^- plasma cells that are Blimp-1⁺. (Figure 4 from Angelin-Duclos, C., G. Cattoretti, K.-I. Lin, and K. Calame. Commitment of B lympho- cytes to a plasma cell fate is associated with Blimp-1 expression in vivo. J. Immunol. 165:5462.)