FIGURE 1.

CD19⁺ B cells are the major Ag-bearing cell type in the PLN 24 h after footpad injection of papain and acquire papain in a non-BCR mediated manner. (A) Representative FACS plots of mice injected in the footpad with 50 μg AF647-labeled papain and sacrificed after 24 h. After gating on MHC-II⁺ cells, cells positive for papain (left panel) were phenotyped, showing that CD19⁺ cells constituted the majority of AF647⁺ cells at 24 h (right panel). (B) Representative FACS plots of CD19⁺ B cells from WT mice 24 h after injection with unlabeled papain, AF647-labeled papain, or AF647-labeled OVA. (C) Quantification of percentages of B cells binding AF647-labeled Ag compared to unlabeled papain controls as described in B. Bars indicate mean ± SD obtained from 2 experiments with n=3 mice per group experiment, *** indicates p<0.001. (D) Representative FACS plots of PLN cells from WT mice injected with AF647-labeled papain as described in (A) and analyzed after 1 h. (E) Representative FACS plots of B cells from WT and MD4 transgenic mice 1 h after injection with AF647-labeled papain. (F) Quantification of the percentages of WT and MD4 B cells acquiring AF647-labeled papain as described in (E). Bars indicate mean ± SD obtained from 2 experiments with n=3 mice per group per experiment, NS indicates no significant difference.