B-cell requirement for LCMV-triggered PLN expansion. (A) Experimental layout for B-cell depletion in WT mice (αCD20 mAb; 250 μg/mouse on day −10) versus B-cell reconstitution and LCMV infection in JHT mice. A total of 2 × 15 to 20 × 106 B cells were injected per JHT recipient on day −2 and 0. (B) Representative OPT images of day 8 (D8)–LCMV-infected inguinal PLNs of WT, WT + αCD20, JHT, and JHT + WT B cells. Scale bar = 400 μm. (C) Inguinal LN volume on day 0 (D0, □) and day 8 (D8, ■) after infection of WT mice, or WT mice + αCD20 mAb or JHT mice reconstituted with WT B cells on day −2 and day 0 after infection. ***P < .001 compared with day 8 LCMV WT (1-way ANOVA). (D) Total HEV network length on day 0 and day 8 after infection as in panel A. All day 8 (D8) values in panels A and B were significantly greater than on corresponding day 0 (Student t test). ***P < .001 compared with day 8 LCMV WT (1-way ANOVA). Numbers indicate fold increase over day 0. No significant difference was found in panels A and B between day 8 “WT” and “JHT + WT B cells” nor between “JHT” and “WT + αCD20” (1-way ANOVA). Pooled from 3 to 8 PLNs from 2 to 6 mice in 2 independent experiments. Data are shown as mean ± SEM.
