Fig. 1.

GC B cell responses in the absence of MZ B cells. (A) Graphic representation of the experimental protocol. (B) Frequencies of GC B cells in WT, CD19 KO, and CD19 KO mice that had been reconstituted with WT MZ B cells 2 wk earlier. The mice were cotransferred with MD4 CD45.1⁺ B cells and OTII T cells, followed by immunization with HEL-OVA in Ribi adjuvant. Mice were immunized i.p. and analyzed 8 d later by flow cytometry. (C) GC responses in peripheral LNs of WT and CD19 KO mice that had been cotransferred with MD4 and OTII cells and immunized s.c. with HEL-OVA, analyzed at 8 d postimmunization. (D) GC B cell responses in CD19 KO and CD19 KO mice reconstituted with WT, CXCR5 KO, or CR1/2 KO B cells as indicated and immunized as above. (E) TSS-KI and WT littermate controls were immunized with NP-CGG. Shown are frequencies of NP-specific GC B cells out of the total B cell population. Data from one of three independently performed experiments are presented.