Comparison of GC formation in IUT, TBI, and control mice.

(A) Splenocytes from an unimmunized C57BL/6 mouse were stained with anti-B220 mAb and PNA, followed by flow cytometric analysis. (B) Splenocytes from a C57BL/6 mouse immunized intraperitoneally with SRBC 8 days previously were stained with anti-B220 mAb and PNA, followed by flow cytometric analysis. Arrow designates the GC B-cell population. (C) IUT, TBI, and control mice were immunized intraperitoneally with SRBC. Spleens were harvested 8 days after immunization and stained with anti-B220 mAb and PNA, followed by flow cytometric analysis. Percentages of GC (B220⁺PNA^high) B cells, as a proportion of total splenic mononuclear cells, were determined by software gating. Each dot represents an individual mouse. Bar graphs represent average GC B-cell frequencies ± SD. Compared with the responses of C57Bl/6 mice (donor strain), Allo NTCD IUT, Allo TCD IUT, and TBI GC responses were significantly reduced (P < .001). IUT mice were immunized starting at 12 weeks of age. Some of the allo IUT mice were challenged at intermediate (20-30 weeks of age) and late (58 weeks of age) time points. TBI mice were challenged starting at 12 weeks after transplantation.