Surface phenotype of OVA-FITC⁺ cells. Unimmunized and OVA/CFA-immunized mice (day 40) were injected with OVA-FITC into the footpad, and 6 hours later LNs and spleen were obtained and processed by flow cytometry. (A) Density plot graphs show CD19 and CD11b expression versus green fluorescence in OVA-FITC–injected mice. The histograms show staining for MHC-II of the gated population; the percentage of cells with a fluorescent intensity over the marker (black line), corresponding to the upper limit of control background staining (gray area) is indicated. (B) Histograms show in black lines the expression of the indicated markers in OVA-FITC⁺ CD11b^high LN cells, and the gray shaded area denotes the expression of the same marker in whole LN cells. The gray lines represent cells stained with an isotype-matched control antibody. One typical experiment of 4 performed is shown (n = 3-4 mice per group).