TI germinal center formation, AID expression, and affinity maturation after immunization with Aβ-peptide liposomes. (A) WT C57BL/6, CD28^−/−, CD40L^−/−, and TCR^−/− mice (n = 5) were immunized with MPLA-containing Aβ1-15 liposomes, and on day 7, spleens were analyzed for germinal center formation by histologic staining with (left panel) PNA, or antibodies against (middle panel) GL-7 or (right panel) AID. (B) GL-7 expression on B220 B cells was also analyzed by flow cytometry after dumping of splenocytes staining positive for IgM, IgD, CD4, CD8, Gr-1, CD11b, and CD11c. Analysis by (C-D) SPR/Biacore and (E) competitive ELISA of average avidity of antibodies in day 7 and day 56 sera from WT and nude mice immunized with Aβ-peptide liposomes.